Commit 0a4e38e6 authored by Alexander Shishkin's avatar Alexander Shishkin Committed by Ingo Molnar
Browse files

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: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: default avatarPeter 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: default avatarIngo Molnar <mingo@kernel.org>
parent 45bfb2e5

include/linux/perf_event.h

+1 −0
Original line number Diff line number Diff line
@@ -174,6 +174,7 @@ struct perf_event; 
 */

#define PERF_PMU_CAP_NO_INTERRUPT		0x01

#define PERF_PMU_CAP_NO_NMI			0x02

#define PERF_PMU_CAP_AUX_NO_SG			0x04



/**

 * struct pmu - generic performance monitoring unit

kernel/events/ring_buffer.c

+50 −6
Original line number Diff line number Diff line
@@ -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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