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perf tools: Start the perf.data mapping at data offset in perf trace

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Currently, we are mapping perf.data in the beginning of the file
and use the data offset as a buffer offset.

This may exceed the mapping area if the data offset is upper than
page_size * mmap_window and result in a page fault (thing that
happen if we merge trace.info in perf.data).

Instead, let's start the mapping in the page that matches our data
offset.

v2: Drop a junk from another patch (trace_report() removal)

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <1254856886-10348-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Frederic Weisbecker 2009-10-06 21:21:26 +02:00 committed by Ingo Molnar
parent 42e59d7d19
commit b209aa1f83
1 changed files with 6 additions and 1 deletions
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7
tools/perf/builtin-trace.c
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@ -143,6 +143,7 @@ static int __cmd_trace(void)
int ret, rc = EXIT_FAILURE;
unsigned long offset = 0;
unsigned long head = 0;
unsigned long shift;
struct stat perf_stat;
event_t *event;
uint32_t size;
@ -180,6 +181,10 @@ static int __cmd_trace(void)
return EXIT_FAILURE;
}
shift = page_size * (head / page_size);
offset += shift;
head -= shift;
remap:
buf = (char *)mmap(NULL, page_size * mmap_window, PROT_READ,
MAP_SHARED, input, offset);
@ -192,9 +197,9 @@ more:
event = (event_t *)(buf + head);
if (head + event->header.size >= page_size * mmap_window) {
unsigned long shift = page_size * (head / page_size);
int res;
shift = page_size * (head / page_size);
res = munmap(buf, page_size * mmap_window);
assert(res == 0);