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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: Peter 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: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2010-05-20 16:46:39 +02:00 committed by Ingo Molnar
parent adb8e118f2
commit 5d967a8be6
2 changed files with 29 additions and 28 deletions
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3
include/linux/perf_event.h
View File

@ -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;
};

54
kernel/perf_event.c
View File

@ -2961,39 +2961,30 @@ again:
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;
offset = handle->offset;
pages_mask = handle->data->nr_pages - 1;
pages = handle->data->data_pages;
do {
unsigned long page_offset;
unsigned long page_size;
int nr;
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);
len -= size;
buf += size;
offset += size;
} while (len);
handle->offset = offset;
handle->offset += len;
/*
* 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);
if (WARN_ON_ONCE(((long)(handle->head - handle->offset)) < 0))
return;
do {
unsigned long size = min(handle->size, len);
memcpy(handle->addr, buf, size);
len -= 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);
}
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;