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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2010-04-05 13:35:57 (GMT) |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2010-04-14 16:20:33 (GMT) |
| commit | 76e1d9047e4edefb8ada20aa90d5762306082bd6 (patch) | |
| tree | 60384bd206878d2c440e07b33d97b1bb00a103dc /include | |
| parent | c05556421742eb47f80301767653a4bcb19de9de (diff) | |
| download | linux-76e1d9047e4edefb8ada20aa90d5762306082bd6.tar.xz | |
perf: Store active software events in a hashlist
Each time a software event triggers, we need to walk through
the entire list of events from the current cpu and task contexts
to retrieve a running perf event that matches.
We also need to check a matching perf event is actually counting.
This walk is wasteful and makes the event fast path scaling
down with a growing number of events running on the same
contexts.
To solve this, we store the running perf events in a hashlist to
get an immediate access to them against their type:event_id when
they trigger.
v2: - Fix SWEVENT_HLIST_SIZE definition (and re-learn some basic
maths along the way)
- Only allocate hlist for online cpus, but keep track of the
refcount on offline possible cpus too, so that we allocate it
if needed when it becomes online.
- Drop the kref use as it's not adapted to our tricks anymore.
v3: - Fix bad refcount check (address instead of value). Thanks to
Eric Dumazet who spotted this.
- While exiting cpu, move the hlist release out of the IPI path
to lock the hlist mutex sanely.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/perf_event.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 6e96cc8..bf896d0 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -589,6 +589,14 @@ enum perf_group_flag { PERF_GROUP_SOFTWARE = 0x1, }; +#define SWEVENT_HLIST_BITS 8 +#define SWEVENT_HLIST_SIZE (1 << SWEVENT_HLIST_BITS) + +struct swevent_hlist { + struct hlist_head heads[SWEVENT_HLIST_SIZE]; + struct rcu_head rcu_head; +}; + /** * struct perf_event - performance event kernel representation: */ @@ -597,6 +605,7 @@ struct perf_event { struct list_head group_entry; struct list_head event_entry; struct list_head sibling_list; + struct hlist_node hlist_entry; int nr_siblings; int group_flags; struct perf_event *group_leader; @@ -744,6 +753,9 @@ struct perf_cpu_context { int active_oncpu; int max_pertask; int exclusive; + struct swevent_hlist *swevent_hlist; + struct mutex hlist_mutex; + int hlist_refcount; /* * Recursion avoidance: |