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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-06-18 11:40:28 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-06-18 14:46:11 +0200 |
| commit | 9d91a6f7a489eb914c16b82d927f9d81d629c259 (patch) | |
| tree | efdccca4b54282bcc941fce5206778d6b0f8e49d /tools/perf/builtin-record.c | |
| parent | 43a21ea81a2400992561146327c4785ce7f7be38 (diff) | |
| download | linux-9d91a6f7a489eb914c16b82d927f9d81d629c259.tar.bz2 | |
perf_counter tools: Handle lost events
Make use of the new ->data_tail mechanism to tell kernel-space
about user-space draining the data stream. Emit lost events
(and display them) if they happen.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'tools/perf/builtin-record.c')
| -rw-r--r-- | tools/perf/builtin-record.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index e1dfef24887f..06fdfb8b4828 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -78,10 +78,10 @@ struct mmap_data { static struct mmap_data mmap_array[MAX_NR_CPUS][MAX_COUNTERS]; -static unsigned int mmap_read_head(struct mmap_data *md) +static unsigned long mmap_read_head(struct mmap_data *md) { struct perf_counter_mmap_page *pc = md->base; - int head; + long head; head = pc->data_head; rmb(); @@ -89,6 +89,17 @@ static unsigned int mmap_read_head(struct mmap_data *md) return head; } +static void mmap_write_tail(struct mmap_data *md, unsigned long tail) +{ + struct perf_counter_mmap_page *pc = md->base; + + /* + * ensure all reads are done before we write the tail out. + */ + /* mb(); */ + pc->data_tail = tail; +} + static void mmap_read(struct mmap_data *md) { unsigned int head = mmap_read_head(md); @@ -109,7 +120,7 @@ static void mmap_read(struct mmap_data *md) * In either case, truncate and restart at head. */ diff = head - old; - if (diff > md->mask / 2 || diff < 0) { + if (diff < 0) { struct timeval iv; unsigned long msecs; @@ -167,6 +178,7 @@ static void mmap_read(struct mmap_data *md) } md->prev = old; + mmap_write_tail(md, old); } static volatile int done = 0; @@ -424,7 +436,7 @@ try_again: mmap_array[nr_cpu][counter].prev = 0; mmap_array[nr_cpu][counter].mask = mmap_pages*page_size - 1; mmap_array[nr_cpu][counter].base = mmap(NULL, (mmap_pages+1)*page_size, - PROT_READ, MAP_SHARED, fd[nr_cpu][counter], 0); + PROT_READ|PROT_WRITE, MAP_SHARED, fd[nr_cpu][counter], 0); if (mmap_array[nr_cpu][counter].base == MAP_FAILED) { error("failed to mmap with %d (%s)\n", errno, strerror(errno)); exit(-1); |