From 0a4e38e64f5e91ce131cc42ee5bb3925377ec840 Mon Sep 17 00:00:00 2001
From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Date: Wed, 14 Jan 2015 14:18:12 +0200
Subject: perf: Support high-order allocations for AUX space
Some pmus (such as BTS or Intel PT without multiple-entry ToPA capability)
don't support scatter-gather and will prefer larger contiguous areas for
their output regions.
This patch adds a new pmu capability to request higher order allocations.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kaixu Xia <kaixu.xia@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Robert Richter <rric@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@infradead.org
Cc: adrian.hunter@intel.com
Cc: kan.liang@intel.com
Cc: markus.t.metzger@intel.com
Cc: mathieu.poirier@linaro.org
Link: http://lkml.kernel.org/r/1421237903-181015-4-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/events/ring_buffer.c | 56 ++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 50 insertions(+), 6 deletions(-)
(limited to 'kernel/events')
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 3de9c4e9ea9f..ed0859e33b2f 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -243,30 +243,74 @@ ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
spin_lock_init(&rb->event_lock);
}
+#define PERF_AUX_GFP (GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_NORETRY)
+
+static struct page *rb_alloc_aux_page(int node, int order)
+{
+ struct page *page;
+
+ if (order > MAX_ORDER)
+ order = MAX_ORDER;
+
+ do {
+ page = alloc_pages_node(node, PERF_AUX_GFP, order);
+ } while (!page && order--);
+
+ if (page && order) {
+ /*
+ * Communicate the allocation size to the driver
+ */
+ split_page(page, order);
+ SetPagePrivate(page);
+ set_page_private(page, order);
+ }
+
+ return page;
+}
+
+static void rb_free_aux_page(struct ring_buffer *rb, int idx)
+{
+ struct page *page = virt_to_page(rb->aux_pages[idx]);
+
+ ClearPagePrivate(page);
+ page->mapping = NULL;
+ __free_page(page);
+}
+
int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event,
pgoff_t pgoff, int nr_pages, int flags)
{
bool overwrite = !(flags & RING_BUFFER_WRITABLE);
int node = (event->cpu == -1) ? -1 : cpu_to_node(event->cpu);
- int ret = -ENOMEM;
+ int ret = -ENOMEM, max_order = 0;
if (!has_aux(event))
return -ENOTSUPP;
+ if (event->pmu->capabilities & PERF_PMU_CAP_AUX_NO_SG)
+ /*
+ * We need to start with the max_order that fits in nr_pages,
+ * not the other way around, hence ilog2() and not get_order.
+ */
+ max_order = ilog2(nr_pages);
+
rb->aux_pages = kzalloc_node(nr_pages * sizeof(void *), GFP_KERNEL, node);
if (!rb->aux_pages)
return -ENOMEM;
rb->free_aux = event->pmu->free_aux;
- for (rb->aux_nr_pages = 0; rb->aux_nr_pages < nr_pages;
- rb->aux_nr_pages++) {
+ for (rb->aux_nr_pages = 0; rb->aux_nr_pages < nr_pages;) {
struct page *page;
+ int last, order;
- page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
+ order = min(max_order, ilog2(nr_pages - rb->aux_nr_pages));
+ page = rb_alloc_aux_page(node, order);
if (!page)
goto out;
- rb->aux_pages[rb->aux_nr_pages] = page_address(page);
+ for (last = rb->aux_nr_pages + (1 << page_private(page));
+ last > rb->aux_nr_pages; rb->aux_nr_pages++)
+ rb->aux_pages[rb->aux_nr_pages] = page_address(page++);
}
rb->aux_priv = event->pmu->setup_aux(event->cpu, rb->aux_pages, nr_pages,
@@ -304,7 +348,7 @@ static void __rb_free_aux(struct ring_buffer *rb)
}
for (pg = 0; pg < rb->aux_nr_pages; pg++)
- free_page((unsigned long)rb->aux_pages[pg]);
+ rb_free_aux_page(rb, pg);
kfree(rb->aux_pages);
rb->aux_nr_pages = 0;
--
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