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Commit 5d967a8b authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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perf: Optimize perf_output_copy() 



Reduce the clutter in perf_output_copy() by keeping
an interator in perf_output_handle.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20100521090710.742809176@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent adb8e118

include/linux/perf_event.h

+3 −0
Original line number Diff line number Diff line
@@ -806,6 +806,9 @@ struct perf_output_handle { 
	unsigned long			head;

	unsigned long			offset;

	unsigned long			wakeup;

	unsigned long			size;

	void				*addr;

	int				page;

	int				nmi;

	int				sample;

};

kernel/perf_event.c

+26 −28
Original line number Diff line number Diff line
@@ -2961,39 +2961,30 @@ static void perf_output_put_handle(struct perf_output_handle *handle) 
void perf_output_copy(struct perf_output_handle *handle,

		      const void *buf, unsigned int len)

{

	unsigned int pages_mask;

	unsigned long offset;

	unsigned int size;

	void **pages;

	handle->offset += len;



	offset		= handle->offset;

	pages_mask	= handle->data->nr_pages - 1;

	pages		= handle->data->data_pages;

	/*

	 * Check we didn't copy past our reservation window, taking the

	 * possible unsigned int wrap into account.

	 */

	if (WARN_ON_ONCE(((long)(handle->head - handle->offset)) < 0))

		return;



	do {

		unsigned long page_offset;

		unsigned long page_size;

		int nr;

		unsigned long size = min(handle->size, len);



		nr	    = (offset >> PAGE_SHIFT) & pages_mask;

		page_size   = 1UL << (handle->data->data_order + PAGE_SHIFT);

		page_offset = offset & (page_size - 1);

		size	    = min_t(unsigned int, page_size - page_offset, len);



		memcpy(pages[nr] + page_offset, buf, size);

		memcpy(handle->addr, buf, size);



		len -= size;

		buf	    += size;

		offset	    += size;

		handle->addr += size;

		handle->size -= size;

		if (!handle->size) {

			handle->page++;

			handle->page &= handle->data->nr_pages - 1;

			handle->addr = handle->data->data_pages[handle->page];

			handle->size = PAGE_SIZE << handle->data->data_order;

		}

	} while (len);



	handle->offset = offset;



	/*

	 * Check we didn't copy past our reservation window, taking the

	 * possible unsigned int wrap into account.

	 */

	WARN_ON_ONCE(((long)(handle->head - handle->offset)) < 0);

}



int perf_output_begin(struct perf_output_handle *handle,
@@ -3059,6 +3050,13 @@ int perf_output_begin(struct perf_output_handle *handle, 
	if (head - local_read(&data->wakeup) > data->watermark)

		local_add(data->watermark, &data->wakeup);



	handle->page = handle->offset >> (PAGE_SHIFT + data->data_order);

	handle->page &= data->nr_pages - 1;

	handle->size = handle->offset & ((PAGE_SIZE << data->data_order) - 1);

	handle->addr = data->data_pages[handle->page];

	handle->addr += handle->size;

	handle->size = (PAGE_SIZE << data->data_order) - handle->size;



	if (have_lost) {

		lost_event.header.type = PERF_RECORD_LOST;

		lost_event.header.misc = 0;