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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-11-20 22:19:45 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-11-21 14:11:35 +0100 |
| commit | 81520183878a8813c71c9372de28bb70913ba549 (patch) | |
| tree | 06604995dae8879091a310a3c9a9cb18d38cf62f /kernel | |
| parent | 0cff784ae41cc125368ae77f1c01328ae2fdc6b3 (diff) | |
| download | linux-81520183878a8813c71c9372de28bb70913ba549.tar.gz linux-81520183878a8813c71c9372de28bb70913ba549.tar.bz2 linux-81520183878a8813c71c9372de28bb70913ba549.zip | |
perf: Optimize perf_swevent_ctx_event()
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: <20091120212508.378188589@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -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 8e55b440e28a..cda17acfcaf8 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -3886,15 +3886,10 @@ static void perf_swevent_ctx_event(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_swevent_match(event, type, event_id, data, regs)) perf_swevent_add(event, nr, nmi, data, regs); } - rcu_read_unlock(); } static int *perf_swevent_recursion_context(struct perf_cpu_context *cpuctx) @@ -3926,9 +3921,9 @@ static void do_perf_sw_event(enum perf_type_id type, u32 event_id, (*recursion)++; barrier(); + rcu_read_lock(); perf_swevent_ctx_event(&cpuctx->ctx, type, event_id, nr, nmi, data, regs); - rcu_read_lock(); /* * doesn't really matter which of the child contexts the * events ends up in. |