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authorPeter Zijlstra <peterz@infradead.org>2023-03-22 14:58:36 +0100
committerPeter Zijlstra <peterz@infradead.org>2023-03-24 11:01:30 +0100
commit5c3124975e15c1fadd5af1c61e4d627cf6d97ba2 (patch)
treee29e216656aa7bc87a9bf6434aab92eb39ca5ad9
parent68e2d17c9eb311ab59aeb6d0c38aad8985fa2596 (diff)
trace,smp: Trace all smp_function_call*() invocations
(Ab)use the trace_ipi_send_cpu*() family to trace all smp_function_call*() invocations, not only those that result in an actual IPI. The queued entries log their callback function while the actual IPIs are traced on generic_smp_call_function_single_interrupt(). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
-rw-r--r--kernel/smp.c66
1 files changed, 36 insertions, 30 deletions
diff --git a/kernel/smp.c b/kernel/smp.c
index 43f0796ecdb2..ab3e5dad6cfe 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -104,18 +104,20 @@ void __init call_function_init(void)
}
static __always_inline void
-send_call_function_single_ipi(int cpu, smp_call_func_t func)
+send_call_function_single_ipi(int cpu)
{
if (call_function_single_prep_ipi(cpu)) {
- trace_ipi_send_cpu(cpu, _RET_IP_, func);
+ trace_ipi_send_cpu(cpu, _RET_IP_,
+ generic_smp_call_function_single_interrupt);
arch_send_call_function_single_ipi(cpu);
}
}
static __always_inline void
-send_call_function_ipi_mask(struct cpumask *mask, smp_call_func_t func)
+send_call_function_ipi_mask(struct cpumask *mask)
{
- trace_ipi_send_cpumask(mask, _RET_IP_, func);
+ trace_ipi_send_cpumask(mask, _RET_IP_,
+ generic_smp_call_function_single_interrupt);
arch_send_call_function_ipi_mask(mask);
}
@@ -316,25 +318,6 @@ static __always_inline void csd_unlock(struct __call_single_data *csd)
smp_store_release(&csd->node.u_flags, 0);
}
-static __always_inline void
-raw_smp_call_single_queue(int cpu, struct llist_node *node, smp_call_func_t func)
-{
- /*
- * The list addition should be visible to the target CPU when it pops
- * the head of the list to pull the entry off it in the IPI handler
- * because of normal cache coherency rules implied by the underlying
- * llist ops.
- *
- * If IPIs can go out of order to the cache coherency protocol
- * in an architecture, sufficient synchronisation should be added
- * to arch code to make it appear to obey cache coherency WRT
- * locking and barrier primitives. Generic code isn't really
- * equipped to do the right thing...
- */
- if (llist_add(node, &per_cpu(call_single_queue, cpu)))
- send_call_function_single_ipi(cpu, func);
-}
-
static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
void __smp_call_single_queue(int cpu, struct llist_node *node)
@@ -354,10 +337,23 @@ void __smp_call_single_queue(int cpu, struct llist_node *node)
func = CSD_TYPE(csd) == CSD_TYPE_TTWU ?
sched_ttwu_pending : csd->func;
- raw_smp_call_single_queue(cpu, node, func);
- } else {
- raw_smp_call_single_queue(cpu, node, NULL);
+ trace_ipi_send_cpu(cpu, _RET_IP_, func);
}
+
+ /*
+ * The list addition should be visible to the target CPU when it pops
+ * the head of the list to pull the entry off it in the IPI handler
+ * because of normal cache coherency rules implied by the underlying
+ * llist ops.
+ *
+ * If IPIs can go out of order to the cache coherency protocol
+ * in an architecture, sufficient synchronisation should be added
+ * to arch code to make it appear to obey cache coherency WRT
+ * locking and barrier primitives. Generic code isn't really
+ * equipped to do the right thing...
+ */
+ if (llist_add(node, &per_cpu(call_single_queue, cpu)))
+ send_call_function_single_ipi(cpu);
}
/*
@@ -732,9 +728,9 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
int cpu, last_cpu, this_cpu = smp_processor_id();
struct call_function_data *cfd;
bool wait = scf_flags & SCF_WAIT;
+ int nr_cpus = 0, nr_queued = 0;
bool run_remote = false;
bool run_local = false;
- int nr_cpus = 0;
lockdep_assert_preemption_disabled();
@@ -776,8 +772,10 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
for_each_cpu(cpu, cfd->cpumask) {
call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
- if (cond_func && !cond_func(cpu, info))
+ if (cond_func && !cond_func(cpu, info)) {
+ __cpumask_clear_cpu(cpu, cfd->cpumask);
continue;
+ }
csd_lock(csd);
if (wait)
@@ -793,17 +791,25 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
nr_cpus++;
last_cpu = cpu;
}
+ nr_queued++;
}
/*
+ * Trace each smp_function_call_*() as an IPI, actual IPIs
+ * will be traced with func==generic_smp_call_function_single_ipi().
+ */
+ if (nr_queued)
+ trace_ipi_send_cpumask(cfd->cpumask, _RET_IP_, func);
+
+ /*
* Choose the most efficient way to send an IPI. Note that the
* number of CPUs might be zero due to concurrent changes to the
* provided mask.
*/
if (nr_cpus == 1)
- send_call_function_single_ipi(last_cpu, func);
+ send_call_function_single_ipi(last_cpu);
else if (likely(nr_cpus > 1))
- send_call_function_ipi_mask(cfd->cpumask_ipi, func);
+ send_call_function_ipi_mask(cfd->cpumask_ipi);
}
if (run_local && (!cond_func || cond_func(this_cpu, info))) {