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The PEBS kernel warnings can still be observed with the below case.
when the below commands are running in parallel for a while.
while true;
do
perf record --no-buildid -a --intr-regs=AX \
-e cpu/event=0xd0,umask=0x81/pp \
-c 10003 -o /dev/null ./triad;
done &
while true;
do
perf record -e 'cpu/mem-loads,ldlat=3/uP' -W -d -- ./dtlb
done
The commit b752ea0c28e3 ("perf/x86/intel/ds: Flush PEBS DS when changing
PEBS_DATA_CFG") intends to flush the entire PEBS buffer before the
hardware is reprogrammed. However, it fails in the above case.
The first perf command utilizes the large PEBS, while the second perf
command only utilizes a single PEBS. When the second perf event is
added, only the n_pebs++. The intel_pmu_pebs_enable() is invoked after
intel_pmu_pebs_add(). So the cpuc->n_pebs == cpuc->n_large_pebs check in
the intel_pmu_drain_large_pebs() fails. The PEBS DS is not flushed.
The new PEBS event should not be taken into account when flushing the
existing PEBS DS.
The check is unnecessary here. Before the hardware is reprogrammed, all
the stale records must be drained unconditionally.
For single PEBS or PEBS-vi-pt, the DS must be empty. The drain_pebs()
can handle the empty case. There is no harm to unconditionally drain the
PEBS DS.
Fixes: b752ea0c28e3 ("perf/x86/intel/ds: Flush PEBS DS when changing PEBS_DATA_CFG")
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20241119135504.1463839-2-kan.liang@linux.intel.com
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From PMU's perspective, the new Arrow Lake U is the same as the
Meteor Lake.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20241121180526.2364759-1-kan.liang@linux.intel.com
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Previously any PMU overflow interrupt that fired while a VCPU was
loaded was recorded as a guest event whether it truly was or not. This
resulted in nonsense perf recordings that did not honor
perf_event_attr.exclude_guest and recorded guest IPs where it should
have recorded host IPs.
Rework the sampling logic to only record guest samples for events with
exclude_guest = 0. This way any host-only events with exclude_guest
set will never see unexpected guest samples. The behaviour of events
with exclude_guest = 0 is unchanged.
Note that events configured to sample both host and guest may still
misattribute a PMI that arrived in the host as a guest event depending
on KVM arch and vendor behavior.
Signed-off-by: Colton Lewis <coltonlewis@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20241113190156.2145593-6-coltonlewis@google.com
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Break the assignment logic for misc flags into their own respective
functions to reduce the complexity of the nested logic.
Signed-off-by: Colton Lewis <coltonlewis@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Acked-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20241113190156.2145593-5-coltonlewis@google.com
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For clarity, rename the arch-specific definitions of these functions
to perf_arch_* to denote they are arch-specifc. Define the
generic-named functions in one place where they can call the
arch-specific ones as needed.
Signed-off-by: Colton Lewis <coltonlewis@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Acked-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Acked-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20241113190156.2145593-3-coltonlewis@google.com
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truncation in amd_uncore_umc_ctx_init
Fix the following warning:
CC [M] arch/x86/events/amd/uncore.o
arch/x86/events/amd/uncore.c: In function ‘amd_uncore_umc_ctx_init’:
arch/x86/events/amd/uncore.c:951:52: warning: ‘%d’ directive output may be truncated writing between 1 and 10 bytes into a region of size 8 [-Wformat-truncation=]
snprintf(pmu->name, sizeof(pmu->name), "amd_umc_%d", index);
^~
arch/x86/events/amd/uncore.c:951:43: note: directive argument in the range [0, 2147483647]
snprintf(pmu->name, sizeof(pmu->name), "amd_umc_%d", index);
^~~~~~~~~~~~
arch/x86/events/amd/uncore.c:951:4: note: ‘snprintf’ output between 10 and 19 bytes into a destination of size 16
snprintf(pmu->name, sizeof(pmu->name), "amd_umc_%d", index);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As far as I can see, there can't be more than UNCORE_GROUP_MAX (256)
groups and each group can't have more than 255 PMU, so the number
printed by this %d can't exceed 65279, that's only 5 digits and would
fit into the buffer. So it's a false positive warning. But we can
make the compiler happy by declaring index as a 16-bit number.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sandipan Das <sandipan.das@amd.com>
Link: https://lore.kernel.org/r/20241105095253.18f34b4d@endymion.delvare
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sampling
Events with aux actions or aux sampling expect the PMI to coincide with the
event, which does not happen for large PEBS, so do not enable large PEBS in
that case.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Link: https://lkml.kernel.org/r/20241022155920.17511-5-adrian.hunter@intel.com
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Prevent tracing to start if aux_paused.
Implement support for PERF_EF_PAUSE / PERF_EF_RESUME. When aux_paused, stop
tracing. When not aux_paused, only start tracing if it isn't currently
meant to be stopped.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Link: https://lkml.kernel.org/r/20241022155920.17511-4-adrian.hunter@intel.com
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If the trace data buffer becomes full, a truncated flag [T] is reported
in PERF_RECORD_AUX. In some cases, the size reported is 0, even though
data must have been added to make the buffer full.
That happens when the buffer fills up from empty to full before the
Intel PT driver has updated the buffer position. Then the driver
calculates the new buffer position before calculating the data size.
If the old and new positions are the same, the data size is reported
as 0, even though it is really the whole buffer size.
Fix by detecting when the buffer position is wrapped, and adjust the
data size calculation accordingly.
Example
Use a very small buffer size (8K) and observe the size of truncated [T]
data. Before the fix, it is possible to see records of 0 size.
Before:
$ perf record -m,8K -e intel_pt// uname
Linux
[ perf record: Woken up 2 times to write data ]
[ perf record: Captured and wrote 0.105 MB perf.data ]
$ perf script -D --no-itrace | grep AUX | grep -F '[T]'
Warning:
AUX data lost 2 times out of 3!
5 19462712368111 0x19710 [0x40]: PERF_RECORD_AUX offset: 0 size: 0 flags: 0x1 [T]
5 19462712700046 0x19ba8 [0x40]: PERF_RECORD_AUX offset: 0x170 size: 0xe90 flags: 0x1 [T]
After:
$ perf record -m,8K -e intel_pt// uname
Linux
[ perf record: Woken up 3 times to write data ]
[ perf record: Captured and wrote 0.040 MB perf.data ]
$ perf script -D --no-itrace | grep AUX | grep -F '[T]'
Warning:
AUX data lost 2 times out of 3!
1 113720802995 0x4948 [0x40]: PERF_RECORD_AUX offset: 0 size: 0x2000 flags: 0x1 [T]
1 113720979812 0x6b10 [0x40]: PERF_RECORD_AUX offset: 0x2000 size: 0x2000 flags: 0x1 [T]
Fixes: 52ca9ced3f70 ("perf/x86/intel/pt: Add Intel PT PMU driver")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20241022155920.17511-2-adrian.hunter@intel.com
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The rapl pmu is die scope, which is supported by the generic perf_event
subsystem now.
Set the scope for the rapl PMU and remove all the cpumask and hotplug
codes.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Oliver Sang <oliver.sang@intel.com>
Tested-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Link: https://lore.kernel.org/r/20241010142604.770192-2-kan.liang@linux.intel.com
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There are extra codes in the CPU hotplug function to allocate rapl pmus.
The generic PMU hotplug support is hard to be applied.
As long as the rapl pmus can be allocated upfront for each die/socket,
the code doesn't need to be implemented in the CPU hotplug function.
Move the code to the init_rapl_pmus(), and allocate a PMU for each
possible die/socket.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Oliver Sang <oliver.sang@intel.com>
Link: https://lore.kernel.org/r/20241010142604.770192-1-kan.liang@linux.intel.com
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Warning at every leaking bits can cause a flood of message, triggering
various stall-warning mechanisms to fire, including CSD locks, which
makes the machine to be unusable.
Track the bits that are being leaked, and only warn when a new bit is
set.
That said, this patch will help with the following issues:
1) It will tell us which bits are being set, so, it is easy to
communicate it back to vendor, and to do a root-cause analyzes.
2) It avoid the machine to be unusable, because, worst case
scenario, the user gets less than 60 WARNs (one per unhandled bit).
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sandipan Das <sandipan.das@amd.com>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lkml.kernel.org/r/20241001141020.2620361-1-leitao@debian.org
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ArrowLake-H contains 3 different uarchs, LionCove, Skymont and Crestmont.
It is different with previous hybrid processors which only contains two
kinds of uarchs.
This patch adds PMU support for ArrowLake-H processor, adds ARL-H
specific events which supports the 3 kinds of uarchs, such as
td_retiring_arl_h, and extends some existed format attributes like
offcore_rsp to make them be available to support ARL-H as well. Althrough
these format attributes like offcore_rsp have been extended to support
ARL-H, they can still support the regular hybrid platforms with 2 kinds
of uarchs since the helper hybrid_format_is_visible() would filter PMU
types and only show the format attribute for available PMUs.
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lkml.kernel.org/r/20240820073853.1974746-5-dapeng1.mi@linux.intel.com
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The upcoming ARL-H hybrid processor contains 2 different atom uarchs
which have different PMU capabilities. To distinguish these atom uarchs,
CPUID.1AH.EAX[23:0] defines a native model ID which can be used to
uniquely identify the uarch of the core by combining with core type.
Thus a 3rd hybrid pmu type "hybrid_tiny" is defined to mark the 2nd
atom uarch. The helper find_hybrid_pmu_for_cpu() would compare the
hybrid pmu type and dynamically read core native id from cpu to identify
the corresponding hybrid pmu structure.
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lkml.kernel.org/r/20240820073853.1974746-4-dapeng1.mi@linux.intel.com
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Use macros instead of magic number to define hybrid_pmu_type and remove
X86_HYBRID_NUM_PMUS since it's never used.
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lkml.kernel.org/r/20240820073853.1974746-2-dapeng1.mi@linux.intel.com
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf events updates from Ingo Molnar:
- Implement per-PMU context rescheduling to significantly improve
single-PMU performance, and related cleanups/fixes (Peter Zijlstra
and Namhyung Kim)
- Fix ancient bug resulting in a lot of events being dropped
erroneously at higher sampling frequencies (Luo Gengkun)
- uprobes enhancements:
- Implement RCU-protected hot path optimizations for better
performance:
"For baseline vs SRCU, peak througput increased from 3.7 M/s
(million uprobe triggerings per second) up to about 8 M/s. For
uretprobes it's a bit more modest with bump from 2.4 M/s to
5 M/s.
For SRCU vs RCU Tasks Trace, peak throughput for uprobes
increases further from 8 M/s to 10.3 M/s (+28%!), and for
uretprobes from 5.3 M/s to 5.8 M/s (+11%), as we have more
work to do on uretprobes side.
Even single-thread (no contention) performance is slightly
better: 3.276 M/s to 3.396 M/s (+3.5%) for uprobes, and 2.055
M/s to 2.174 M/s (+5.8%) for uretprobes."
(Andrii Nakryiko et al)
- Document mmap_lock, don't abuse get_user_pages_remote() (Oleg
Nesterov)
- Cleanups & fixes to prepare for future work:
- Remove uprobe_register_refctr()
- Simplify error handling for alloc_uprobe()
- Make uprobe_register() return struct uprobe *
- Fold __uprobe_unregister() into uprobe_unregister()
- Shift put_uprobe() from delete_uprobe() to uprobe_unregister()
- BPF: Fix use-after-free in bpf_uprobe_multi_link_attach()
(Oleg Nesterov)
- New feature & ABI extension: allow events to use PERF_SAMPLE READ
with inheritance, enabling sample based profiling of a group of
counters over a hierarchy of processes or threads (Ben Gainey)
- Intel uncore & power events updates:
- Add Arrow Lake and Lunar Lake support
- Add PERF_EV_CAP_READ_SCOPE
- Clean up and enhance cpumask and hotplug support
(Kan Liang)
- Add LNL uncore iMC freerunning support
- Use D0:F0 as a default device
(Zhenyu Wang)
- Intel PT: fix AUX snapshot handling race (Adrian Hunter)
- Misc fixes and cleanups (James Clark, Jiri Olsa, Oleg Nesterov and
Peter Zijlstra)
* tag 'perf-core-2024-09-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits)
dmaengine: idxd: Clean up cpumask and hotplug for perfmon
iommu/vt-d: Clean up cpumask and hotplug for perfmon
perf/x86/intel/cstate: Clean up cpumask and hotplug
perf: Add PERF_EV_CAP_READ_SCOPE
perf: Generic hotplug support for a PMU with a scope
uprobes: perform lockless SRCU-protected uprobes_tree lookup
rbtree: provide rb_find_rcu() / rb_find_add_rcu()
perf/uprobe: split uprobe_unregister()
uprobes: travers uprobe's consumer list locklessly under SRCU protection
uprobes: get rid of enum uprobe_filter_ctx in uprobe filter callbacks
uprobes: protected uprobe lifetime with SRCU
uprobes: revamp uprobe refcounting and lifetime management
bpf: Fix use-after-free in bpf_uprobe_multi_link_attach()
perf/core: Fix small negative period being ignored
perf: Really fix event_function_call() locking
perf: Optimize __pmu_ctx_sched_out()
perf: Add context time freeze
perf: Fix event_function_call() locking
perf: Extract a few helpers
perf: Optimize context reschedule for single PMU cases
...
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The BPF subsystem may capture LBR data on a counting event. However, the
current implementation assumes that LBR can/should only be used with
sampling events.
For instance, retsnoop tool ([0]) makes an extensive use of this
functionality and sets up perf event as follows:
struct perf_event_attr attr;
memset(&attr, 0, sizeof(attr));
attr.size = sizeof(attr);
attr.type = PERF_TYPE_HARDWARE;
attr.config = PERF_COUNT_HW_CPU_CYCLES;
attr.sample_type = PERF_SAMPLE_BRANCH_STACK;
attr.branch_sample_type = PERF_SAMPLE_BRANCH_KERNEL;
To limit the LBR for a sampling event is to avoid unnecessary branch
stack setup for a counting event in the sample read. Because LBR is only
read in the sampling event's overflow.
Although in most cases LBR is used in sampling, there is no HW limit to
bind LBR to the sampling mode. Allow an LBR setup for a counting event
unless in the sample read mode.
Fixes: 85846b27072d ("perf/x86: Add PERF_X86_EVENT_NEEDS_BRANCH_STACK flag")
Closes: https://lore.kernel.org/lkml/20240905180055.1221620-1-andrii@kernel.org/
Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240909155848.326640-1-kan.liang@linux.intel.com
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There are three cstate PMUs with different scopes, core, die and module.
The scopes are supported by the generic perf_event subsystem now.
Set the scope for each PMU and remove all the cpumask and hotplug codes.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240802151643.1691631-4-kan.liang@linux.intel.com
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After commit:
63edbaa48a57 ("x86/cpu/topology: Add support for the AMD 0x80000026 leaf")
... on AMD processors that support extended CPUID leaf 0x80000026, the
topology_die_cpumask() and topology_logical_die_id() macros no longer
return the package cpumask and package ID, instead they return the CCD
(Core Complex Die) mask and ID respectively.
This leads to the energy-pkg event scope to be modified to CCD instead of package.
So, change the PMU scope for AMD and Hygon back to package.
On a 12 CCD 1 Package AMD Zen4 Genoa machine:
Before:
$ cat /sys/devices/power/cpumask
0,8,16,24,32,40,48,56,64,72,80,88.
The expected cpumask here is supposed to be just "0", as it is a package
scope event, only one CPU will be collecting the event for all the CPUs in
the package.
After:
$ cat /sys/devices/power/cpumask
0
[ mingo: Cleaned up the changelog ]
Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20240904100934.3260-1-Dhananjay.Ugwekar@amd.com
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This also refreshes the -rc1 based branch to -rc5.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Running the ltp test cve-2015-3290 concurrently reports the following
warnings.
perfevents: irq loop stuck!
WARNING: CPU: 31 PID: 32438 at arch/x86/events/intel/core.c:3174
intel_pmu_handle_irq+0x285/0x370
Call Trace:
<NMI>
? __warn+0xa4/0x220
? intel_pmu_handle_irq+0x285/0x370
? __report_bug+0x123/0x130
? intel_pmu_handle_irq+0x285/0x370
? __report_bug+0x123/0x130
? intel_pmu_handle_irq+0x285/0x370
? report_bug+0x3e/0xa0
? handle_bug+0x3c/0x70
? exc_invalid_op+0x18/0x50
? asm_exc_invalid_op+0x1a/0x20
? irq_work_claim+0x1e/0x40
? intel_pmu_handle_irq+0x285/0x370
perf_event_nmi_handler+0x3d/0x60
nmi_handle+0x104/0x330
Thanks to Thomas Gleixner's analysis, the issue is caused by the low
initial period (1) of the frequency estimation algorithm, which triggers
the defects of the HW, specifically erratum HSW11 and HSW143. (For the
details, please refer https://lore.kernel.org/lkml/87plq9l5d2.ffs@tglx/)
The HSW11 requires a period larger than 100 for the INST_RETIRED.ALL
event, but the initial period in the freq mode is 1. The erratum is the
same as the BDM11, which has been supported in the kernel. A minimum
period of 128 is enforced as well on HSW.
HSW143 is regarding that the fixed counter 1 may overcount 32 with the
Hyper-Threading is enabled. However, based on the test, the hardware
has more issues than it tells. Besides the fixed counter 1, the message
'interrupt took too long' can be observed on any counter which was armed
with a period < 32 and two events expired in the same NMI. A minimum
period of 32 is enforced for the rest of the events.
The recommended workaround code of the HSW143 is not implemented.
Because it only addresses the issue for the fixed counter. It brings
extra overhead through extra MSR writing. No related overcounting issue
has been reported so far.
Fixes: 3a632cb229bf ("perf/x86/intel: Add simple Haswell PMU support")
Reported-by: Li Huafei <lihuafei1@huawei.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240819183004.3132920-1-kan.liang@linux.intel.com
Closes: https://lore.kernel.org/lkml/20240729223328.327835-1-lihuafei1@huawei.com/
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The default paranoid setting was updated in commit 0161028b7c8a
("perf/core: Change the default paranoia level to 2") so this comment is
no longer true.
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20240802105256.335961-1-james.clark@linaro.org
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Some uncore PMON registers are located in the MMIO space of the Host
Bridge and DRAM Controller device, which is located at D0:F0 for
Tiger Lake and later client generation.
Use D0:F0 as a default device. So it doesn't need to keep adding the
complete Device ID list for each generation anymore.
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20240731141353.759643-5-kan.liang@linux.intel.com
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LNL uncore imc freerunning counters keep same as previous HW.
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20240731141353.759643-4-kan.liang@linux.intel.com
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The uncore subsystem for Lunar Lake is similar to the previous
Meteor Lake. The uncore PerfMon registers are located at both
MSR and MMIO space.
The ARB and iMC are kept. There is no difference from the Meteor Lake.
Move the global control initialization to the first box of the CBOX.
The sNCU is moved to the MMIO space.
The HBO is newly added and only be accessed from the MMIO space.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240731141353.759643-3-kan.liang@linux.intel.com
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Some uncore PMON registers are located in the MMIO space. For the client
machine, the MMIO space is usually located at D0:F0 but in a different
BAR. For example, some uncore PMON registers are located in the SAF BAR,
not the MCHBAR in the Lunar Lake.
The current __uncore_imc_init_box() hard code the BAR information.
Factor out the uncore_get_box_mmio_addr() which uses the BAR information
as a parameter.
The only change is the error output message. The hardcode name 'MCHBAR'
is replaced by the offset of a BAR.
Add a new macro, MMIO_UNCORE_COMMON_OPS(), since the MMIO ops functions
are usually the same among different generations.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240731141353.759643-2-kan.liang@linux.intel.com
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>From the perspective of the uncore PMU, the Arrow Lake is the same as
the previous Meteor Lake. The only difference is the event list, which
will be supported in the perf tool later.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240731141353.759643-1-kan.liang@linux.intel.com
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When tracing user functions with uprobe functionality, it's common to
install the probe (e.g., a BPF program) at the first instruction of the
function. This is often going to be `push %rbp` instruction in function
preamble, which means that within that function frame pointer hasn't
been established yet. This leads to consistently missing an actual
caller of the traced function, because perf_callchain_user() only
records current IP (capturing traced function) and then following frame
pointer chain (which would be caller's frame, containing the address of
caller's caller).
So when we have target_1 -> target_2 -> target_3 call chain and we are
tracing an entry to target_3, captured stack trace will report
target_1 -> target_3 call chain, which is wrong and confusing.
This patch proposes a x86-64-specific heuristic to detect `push %rbp`
(`push %ebp` on 32-bit architecture) instruction being traced. Given
entire kernel implementation of user space stack trace capturing works
under assumption that user space code was compiled with frame pointer
register (%rbp/%ebp) preservation, it seems pretty reasonable to use
this instruction as a strong indicator that this is the entry to the
function. In that case, return address is still pointed to by %rsp/%esp,
so we fetch it and add to stack trace before proceeding to unwind the
rest using frame pointer-based logic.
We also check for `endbr64` (for 64-bit modes) as another common pattern
for function entry, as suggested by Josh Poimboeuf. Even if we get this
wrong sometimes for uprobes attached not at the function entry, it's OK
because stack trace will still be overall meaningful, just with one
extra bogus entry. If we don't detect this, we end up with guaranteed to
be missing caller function entry in the stack trace, which is worse
overall.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20240729175223.23914-1-andrii@kernel.org
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The following bug was triggered on a system built with
CONFIG_DEBUG_PREEMPT=y:
# echo p > /proc/sysrq-trigger
BUG: using smp_processor_id() in preemptible [00000000] code: sh/117
caller is perf_event_print_debug+0x1a/0x4c0
CPU: 3 UID: 0 PID: 117 Comm: sh Not tainted 6.11.0-rc1 #109
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x4f/0x60
check_preemption_disabled+0xc8/0xd0
perf_event_print_debug+0x1a/0x4c0
__handle_sysrq+0x140/0x180
write_sysrq_trigger+0x61/0x70
proc_reg_write+0x4e/0x70
vfs_write+0xd0/0x430
? handle_mm_fault+0xc8/0x240
ksys_write+0x9c/0xd0
do_syscall_64+0x96/0x190
entry_SYSCALL_64_after_hwframe+0x4b/0x53
This is because the commit d4b294bf84db ("perf/x86: Hybrid PMU support
for counters") took smp_processor_id() outside the irq critical section.
If a preemption occurs in perf_event_print_debug() and the task is
migrated to another cpu, we may get incorrect pmu debug information.
Move smp_processor_id() back inside the irq critical section to fix this
issue.
Fixes: d4b294bf84db ("perf/x86: Hybrid PMU support for counters")
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Reviewed-and-tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20240729220928.325449-1-lihuafei1@huawei.com
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Start a new section for AUX PMUs in hw_perf_event.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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pt_event_snapshot_aux() uses pt->handle_nmi to determine if tracing
needs to be stopped, however tracing can still be going because
pt->handle_nmi is set to zero before tracing is stopped in pt_event_stop,
whereas pt_event_snapshot_aux() requires that tracing must be stopped in
order to copy a sample of trace from the buffer.
Instead call pt_config_stop() always, which anyway checks config for
RTIT_CTL_TRACEEN and does nothing if it is already clear.
Note pt_event_snapshot_aux() can continue to use pt->handle_nmi to
determine if the trace needs to be restarted afterwards.
Fixes: 25e8920b301c ("perf/x86/intel/pt: Add sampling support")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20240715160712.127117-2-adrian.hunter@intel.com
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Package C2 residency counter is also available on Sierra Forest.
So add it support in srf_cstates.
Fixes: 3877d55a0db2 ("perf/x86/intel/cstate: Add Sierra Forest support")
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Wendy Wang <wendy.wang@intel.com>
Link: https://lore.kernel.org/r/20240717031609.74513-1-zhenyuw@linux.intel.com
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull performance events updates from Ingo Molnar:
- Intel PT support enhancements & fixes
- Fix leaked SIGTRAP events
- Improve and fix the Intel uncore driver
- Add support for Intel HBM and CXL uncore counters
- Add Intel Lake and Arrow Lake support
- AMD uncore driver fixes
- Make SIGTRAP and __perf_pending_irq() work on RT
- Micro-optimizations
- Misc cleanups and fixes
* tag 'perf-core-2024-07-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
perf/x86/intel: Add a distinct name for Granite Rapids
perf/x86/intel/ds: Fix non 0 retire latency on Raptorlake
perf/x86/intel: Hide Topdown metrics events if the feature is not enumerated
perf/x86/intel/uncore: Fix the bits of the CHA extended umask for SPR
perf: Split __perf_pending_irq() out of perf_pending_irq()
perf: Don't disable preemption in perf_pending_task().
perf: Move swevent_htable::recursion into task_struct.
perf: Shrink the size of the recursion counter.
perf: Enqueue SIGTRAP always via task_work.
task_work: Add TWA_NMI_CURRENT as an additional notify mode.
perf: Move irq_work_queue() where the event is prepared.
perf: Fix event leak upon exec and file release
perf: Fix event leak upon exit
task_work: Introduce task_work_cancel() again
task_work: s/task_work_cancel()/task_work_cancel_func()/
perf/x86/amd/uncore: Fix DF and UMC domain identification
perf/x86/amd/uncore: Avoid PMU registration if counters are unavailable
perf/x86/intel: Support Perfmon MSRs aliasing
perf/x86/intel: Support PERFEVTSEL extension
perf/x86: Add config_mask to represent EVENTSEL bitmask
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
- Jump label fixes, including a perf events fix that originally
manifested as jump label failures, but was a serialization bug at the
usage site
- Mark down_write*() helpers as __always_inline, to improve WCHAN
debuggability
- Misc cleanups and fixes
* tag 'locking-core-2024-07-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/rwsem: Add __always_inline annotation to __down_write_common() and inlined callers
jump_label: Simplify and clarify static_key_fast_inc_cpus_locked()
jump_label: Clarify condition in static_key_fast_inc_not_disabled()
jump_label: Fix concurrency issues in static_key_slow_dec()
perf/x86: Serialize set_attr_rdpmc()
cleanup: Standardize the header guard define's name
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpu model updates from Borislav Petkov:
- Flip the logic to add feature names to /proc/cpuinfo to having to
explicitly specify the flag if there's a valid reason to show it in
/proc/cpuinfo
- Switch a bunch of Intel x86 model checking code to the new CPU model
defines
- Fixes and cleanups
* tag 'x86_cpu_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/cpu/intel: Drop stray FAM6 check with new Intel CPU model defines
x86/cpufeatures: Flip the /proc/cpuinfo appearance logic
x86/CPU/AMD: Always inline amd_clear_divider()
x86/mce/inject: Add missing MODULE_DESCRIPTION() line
perf/x86/rapl: Switch to new Intel CPU model defines
x86/boot: Switch to new Intel CPU model defines
x86/cpu: Switch to new Intel CPU model defines
perf/x86/intel: Switch to new Intel CPU model defines
x86/virt/tdx: Switch to new Intel CPU model defines
x86/PCI: Switch to new Intel CPU model defines
x86/cpu/intel: Switch to new Intel CPU model defines
x86/platform/intel-mid: Switch to new Intel CPU model defines
x86/pconfig: Remove unused MKTME pconfig code
x86/cpu: Remove useless work in detect_tme_early()
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Currently, the Sapphire Rapids and Granite Rapids share the same PMU
name, sapphire_rapids. Because from the kernel’s perspective, GNR is
similar to SPR. The only key difference is that they support different
extra MSRs. The code path and the PMU name are shared.
However, from end users' perspective, they are quite different. Besides
the extra MSRs, GNR has a newer PEBS format, supports Retire Latency,
supports new CPUID enumeration architecture, doesn't required the
load-latency AUX event, has additional TMA Level 1 Architectural Events,
etc. The differences can be enumerated by CPUID or the PERF_CAPABILITIES
MSR. They weren't reflected in the model-specific kernel setup.
But it is worth to have a distinct PMU name for GNR.
Fixes: a6742cb90b56 ("perf/x86/intel: Fix the FRONTEND encoding on GNR and MTL")
Suggested-by: Ahmad Yasin <ahmad.yasin@intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20240708193336.1192217-3-kan.liang@linux.intel.com
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A non-0 retire latency can be observed on a Raptorlake which doesn't
support the retire latency feature.
By design, the retire latency shares the PERF_SAMPLE_WEIGHT_STRUCT
sample type with other types of latency. That could avoid adding too
many different sample types to support all kinds of latency. For the
machine which doesn't support some kind of latency, 0 should be
returned.
Perf doesn’t clear/init all the fields of a sample data for the sake
of performance. It expects the later perf_{prepare,output}_sample() to
update the uninitialized field. However, the current implementation
doesn't touch the field of the retire latency if the feature is not
supported. The memory garbage is dumped into the perf data.
Clear the retire latency if the feature is not supported.
Fixes: c87a31093c70 ("perf/x86: Support Retire Latency")
Reported-by: "Bayduraev, Alexey V" <alexey.v.bayduraev@intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: "Bayduraev, Alexey V" <alexey.v.bayduraev@intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20240708193336.1192217-4-kan.liang@linux.intel.com
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The below error is observed on Ice Lake VM.
$ perf stat
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument)
for event (slots).
/bin/dmesg | grep -i perf may provide additional information.
In a virtualization env, the Topdown metrics and the slots event haven't
been supported yet. The guest CPUID doesn't enumerate them. However, the
current kernel unconditionally exposes the slots event and the Topdown
metrics events to sysfs, which misleads the perf tool and triggers the
error.
Hide the perf-metrics topdown events and the slots event if the
perf-metrics feature is not enumerated.
The big core of a hybrid platform can also supports the perf-metrics
feature. Fix the hybrid platform as well.
Closes: https://lore.kernel.org/lkml/CAM9d7cj8z+ryyzUHR+P1Dcpot2jjW+Qcc4CPQpfafTXN=LEU0Q@mail.gmail.com/
Reported-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Dongli Zhang <dongli.zhang@oracle.com>
Link: https://lkml.kernel.org/r/20240708193336.1192217-2-kan.liang@linux.intel.com
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The perf stat errors out with UNC_CHA_TOR_INSERTS.IA_HIT_CXL_ACC_LOCAL
event.
$perf stat -e uncore_cha_55/event=0x35,umask=0x10c0008101/ -a -- ls
event syntax error: '..0x35,umask=0x10c0008101/'
\___ Bad event or PMU
The definition of the CHA umask is config:8-15,32-55, which is 32bit.
However, the umask of the event is bigger than 32bit.
This is an error in the original uncore spec.
Add a new umask_ext5 for the new CHA umask range.
Fixes: 949b11381f81 ("perf/x86/intel/uncore: Add Sapphire Rapids server CHA support")
Closes: https://lore.kernel.org/linux-perf-users/alpine.LRH.2.20.2401300733310.11354@Diego/
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20240708185524.1185505-1-kan.liang@linux.intel.com
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For uncore PMUs, a single context is shared across all CPUs in a domain.
The domain can be a CCX, like in the case of the L3 PMU, or a socket,
like in the case of DF and UMC PMUs. This information is available via
the PMU's cpumask.
For contexts shared across a socket, the domain is currently determined
from topology_die_id() which is incorrect after the introduction of
commit 63edbaa48a57 ("x86/cpu/topology: Add support for the AMD
0x80000026 leaf") as it now returns a CCX identifier on Zen 4 and later
systems which support CPUID leaf 0x80000026.
Use topology_logical_package_id() instead as it always returns a socket
identifier irrespective of the availability of CPUID leaf 0x80000026.
Fixes: 63edbaa48a57 ("x86/cpu/topology: Add support for the AMD 0x80000026 leaf")
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20240626074942.1044818-1-sandipan.das@amd.com
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X86_FEATURE_PERFCTR_NB and X86_FEATURE_PERFCTR_LLC are derived from
CPUID leaf 0x80000001 ECX bits 24 and 28 respectively and denote the
availability of DF and L3 counters. When these bits are not set, the
corresponding PMUs have no counters and hence, should not be registered.
Fixes: 07888daa056e ("perf/x86/amd/uncore: Move discovery and registration")
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20240626074404.1044230-1-sandipan.das@amd.com
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The architectural performance monitoring V6 supports a new range of
counters' MSRs in the 19xxH address range. They include all the GP
counter MSRs, the GP control MSRs, and the fixed counter MSRs.
The step between each sibling counter is 4. Add intel_pmu_addr_offset()
to calculate the correct offset.
Add fixedctr in struct x86_pmu to store the address of the fixed counter
0. It can be used to calculate the rest of the fixed counters.
The MSR address of the fixed counter control is not changed.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lkml.kernel.org/r/20240626143545.480761-9-kan.liang@linux.intel.com
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Two new fields (the unit mask2, and the equal flag) are added in the
IA32_PERFEVTSELx MSRs. They can be enumerated by the CPUID.23H.0.EBX.
Update the config_mask in x86_pmu and x86_hybrid_pmu for the true layout
of the PERFEVTSEL.
Expose the new formats into sysfs if they are available. The umask
extension reuses the same format attr name "umask" as the previous
umask. Add umask2_show to determine/display the correct format
for the current machine.
Co-developed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lkml.kernel.org/r/20240626143545.480761-8-kan.liang@linux.intel.com
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Different vendors may support different fields in EVENTSEL MSR, such as
Intel would introduce new fields umask2 and eq bits in EVENTSEL MSR
since Perfmon version 6. However, a fixed mask X86_RAW_EVENT_MASK is
used to filter the attr.config.
Introduce a new config_mask to record the real supported EVENTSEL
bitmask.
Only apply it to the existing code now. No functional change.
Co-developed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lkml.kernel.org/r/20240626143545.480761-7-kan.liang@linux.intel.com
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A new PEBS data source format is introduced for the p-core of Lunar
Lake. The data source field is extended to 8 bits with new encodings.
A new layout is introduced into the union intel_x86_pebs_dse.
Introduce the lnl_latency_data() to parse the new format.
Enlarge the pebs_data_source[] accordingly to include new encodings.
Only the mem load and the mem store events can generate the data source.
Introduce INTEL_HYBRID_LDLAT_CONSTRAINT and
INTEL_HYBRID_STLAT_CONSTRAINT to mark them.
Add two new bits for the new cache-related data src, L2_MHB and MSC.
The L2_MHB is short for L2 Miss Handling Buffer, which is similar to
LFB (Line Fill Buffer), but to track the L2 Cache misses.
The MSC stands for the memory-side cache.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lkml.kernel.org/r/20240626143545.480761-6-kan.liang@linux.intel.com
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The model-specific pebs_latency_data functions of ADL and MTL use the
"small" as a postfix to indicate the e-core. The postfix is too generic
for a model-specific function. It cannot provide useful information that
can directly map it to a specific uarch, which can facilitate the
development and maintenance.
Use the abbr of the uarch to rename the model-specific functions.
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lkml.kernel.org/r/20240626143545.480761-5-kan.liang@linux.intel.com
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From PMU's perspective, Lunar Lake and Arrow Lake are similar to the
previous generation Meteor Lake. Both are hybrid platforms, with e-core
and p-core.
The key differences include:
- The e-core supports 3 new fixed counters
- The p-core supports an updated PEBS Data Source format
- More GP counters (Updated event constraint table)
- New Architectural performance monitoring V6
(New Perfmon MSRs aliasing, umask2, eq).
- New PEBS format V6 (Counters Snapshotting group)
- New RDPMC metrics clear mode
The legacy features, the 3 new fixed counters and updated event
constraint table are enabled in this patch.
The new PEBS data source format, the architectural performance
monitoring V6, the PEBS format V6, and the new RDPMC metrics clear mode
are supported in the following patches.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lkml.kernel.org/r/20240626143545.480761-4-kan.liang@linux.intel.com
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The current perf assumes that both GP and fixed counters are contiguous.
But it's not guaranteed on newer Intel platforms or in a virtualization
environment.
Use the counter mask to replace the number of counters for both GP and
the fixed counters. For the other ARCHs or old platforms which don't
support a counter mask, using GENMASK_ULL(num_counter - 1, 0) to
replace. There is no functional change for them.
The interface to KVM is not changed. The number of counters still be
passed to KVM. It can be updated later separately.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lkml.kernel.org/r/20240626143545.480761-3-kan.liang@linux.intel.com
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The current perf assumes that the counters that support PEBS are
contiguous. But it's not guaranteed with the new leaf 0x23 introduced.
The counters are enumerated with a counter mask. There may be holes in
the counter mask for future platforms or in a virtualization
environment.
Store the PEBS event mask rather than the maximum number of PEBS
counters in the x86 PMU structures.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lkml.kernel.org/r/20240626143545.480761-2-kan.liang@linux.intel.com
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