lkml.org 
[lkml]   [2019]   [Oct]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip: perf/core] perf/core: Optimize perf_init_event() for TYPE_SOFTWARE
The following commit has been merged into the perf/core branch of tip:

Commit-ID: d44f821b0e13275735e8f3fe4db8703b45f05d52
Gitweb: https://git.kernel.org/tip/d44f821b0e13275735e8f3fe4db8703b45f05d52
Author: Liang, Kan <kan.liang@linux.intel.com>
AuthorDate: Tue, 22 Oct 2019 11:13:09 +02:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Mon, 28 Oct 2019 12:53:28 +01:00

perf/core: Optimize perf_init_event() for TYPE_SOFTWARE

Andi reported that he was hitting the linear search in
perf_init_event() a lot. Now that all !TYPE_SOFTWARE events should hit
the IDR, make sure the TYPE_SOFTWARE events are at the head of the
list such that we'll quickly find the right PMU (provided a valid
event was given).

Signed-off-by: Liang, Kan <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/events/core.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4d67c5d..cfd89b4 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10180,7 +10180,16 @@ got_cpu_context:
if (!pmu->event_idx)
pmu->event_idx = perf_event_idx_default;

- list_add_rcu(&pmu->entry, &pmus);
+ /*
+ * Ensure the TYPE_SOFTWARE PMUs are at the head of the list,
+ * since these cannot be in the IDR. This way the linear search
+ * is fast, provided a valid software event is provided.
+ */
+ if (type == PERF_TYPE_SOFTWARE || !name)
+ list_add_rcu(&pmu->entry, &pmus);
+ else
+ list_add_tail_rcu(&pmu->entry, &pmus);
+
atomic_set(&pmu->exclusive_cnt, 0);
ret = 0;
unlock:
\
 
 \ /
  Last update: 2019-10-28 13:49    [W:0.230 / U:0.196 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site