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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-11-20 22:19:48 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-11-21 14:11:37 +0100 |
| commit | f6d9dd237da400effb265f3554c64413f8a3e7b4 (patch) | |
| tree | d06e7ec3385697a638b18c6890c087f0ac8e329b /kernel/perf_event.c | |
| parent | f6595f3a9680c86b6332f881a7ae2cbbcfdc8619 (diff) | |
| download | linux-f6d9dd237da400effb265f3554c64413f8a3e7b4.tar.gz linux-f6d9dd237da400effb265f3554c64413f8a3e7b4.tar.bz2 linux-f6d9dd237da400effb265f3554c64413f8a3e7b4.zip | |
perf: Optimize perf_event_mmap_ctx()
Remove a rcu_read_{,un}lock() pair and a few conditionals.
We can remove the rcu_read_lock() by increasing the scope of one
in the calling function.
We can do away with the system_state check if the machine still
boots after this patch (seems to be the case).
We can do away with the list_empty() check because the bare
list_for_each_entry_rcu() reduces to that now that we've removed
everything else.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091120212508.606459548@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_event.c')
| -rw-r--r-- | kernel/perf_event.c | 7 |
1 files changed, 1 insertions, 6 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 4deefaace90e..68fbf4ff6888 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -3493,15 +3493,10 @@ static void perf_event_mmap_ctx(struct perf_event_context *ctx, { struct perf_event *event; - if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list)) - return; - - rcu_read_lock(); list_for_each_entry_rcu(event, &ctx->event_list, event_entry) { if (perf_event_mmap_match(event, mmap_event)) perf_event_mmap_output(event, mmap_event); } - rcu_read_unlock(); } static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) @@ -3557,11 +3552,11 @@ got_name: mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size; + rcu_read_lock(); cpuctx = &get_cpu_var(perf_cpu_context); perf_event_mmap_ctx(&cpuctx->ctx, mmap_event); put_cpu_var(perf_cpu_context); - rcu_read_lock(); /* * doesn't really matter which of the child contexts the * events ends up in. |