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Message-ID: <tip-6bde9b6ce0127e2a56228a2071536d422be31336@git.kernel.org>
Date: Fri, 7 May 2010 18:44:32 GMT
From: tip-bot for Lin Ming <ming.m.lin@...el.com>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, paulus@...ba.org, eranian@...gle.com,
hpa@...or.com, mingo@...hat.com, a.p.zijlstra@...llo.nl,
davem@...emloft.net, fweisbec@...il.com, ming.m.lin@...el.com,
tglx@...utronix.de, mingo@...e.hu
Subject: [tip:perf/core] perf: Add group scheduling transactional APIs
Commit-ID: 6bde9b6ce0127e2a56228a2071536d422be31336
Gitweb: http://git.kernel.org/tip/6bde9b6ce0127e2a56228a2071536d422be31336
Author: Lin Ming <ming.m.lin@...el.com>
AuthorDate: Fri, 23 Apr 2010 13:56:00 +0800
Committer: Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 7 May 2010 11:31:02 +0200
perf: Add group scheduling transactional APIs
Add group scheduling transactional APIs to struct pmu.
These APIs will be implemented in arch code, based on Peter's idea as
below.
> the idea behind hw_perf_group_sched_in() is to not perform
> schedulability tests on each event in the group, but to add the group
> as a whole and then perform one test.
>
> Of course, when that test fails, you'll have to roll-back the whole
> group again.
>
> So start_txn (or a better name) would simply toggle a flag in the pmu
> implementation that will make pmu::enable() not perform the
> schedulablilty test.
>
> Then commit_txn() will perform the schedulability test (so note the
> method has to have a !void return value.
>
> This will allow us to use the regular
> kernel/perf_event.c::group_sched_in() and all the rollback code.
> Currently each hw_perf_group_sched_in() implementation duplicates all
> the rolllback code (with various bugs).
->start_txn:
Start group events scheduling transaction, set a flag to make
pmu::enable() not perform the schedulability test, it will be performed
at commit time.
->commit_txn:
Commit group events scheduling transaction, perform the group
schedulability as a whole
->cancel_txn:
Stop group events scheduling transaction, clear the flag so
pmu::enable() will perform the schedulability test.
Reviewed-by: Stephane Eranian <eranian@...gle.com>
Reviewed-by: Frederic Weisbecker <fweisbec@...il.com>
Signed-off-by: Lin Ming <ming.m.lin@...el.com>
Cc: David Miller <davem@...emloft.net>
Cc: Paul Mackerras <paulus@...ba.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
LKML-Reference: <1272002160.5707.60.camel@...ggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
include/linux/perf_event.h | 15 ++++++++++++---
kernel/perf_event.c | 33 ++++++++++++++++++++-------------
2 files changed, 32 insertions(+), 16 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 23cd005..4924c96 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -547,6 +547,8 @@ struct hw_perf_event {
struct perf_event;
+#define PERF_EVENT_TXN_STARTED 1
+
/**
* struct pmu - generic performance monitoring unit
*/
@@ -557,6 +559,16 @@ struct pmu {
void (*stop) (struct perf_event *event);
void (*read) (struct perf_event *event);
void (*unthrottle) (struct perf_event *event);
+
+ /*
+ * group events scheduling is treated as a transaction,
+ * add group events as a whole and perform one schedulability test.
+ * If test fails, roll back the whole group
+ */
+
+ void (*start_txn) (const struct pmu *pmu);
+ void (*cancel_txn) (const struct pmu *pmu);
+ int (*commit_txn) (const struct pmu *pmu);
};
/**
@@ -823,9 +835,6 @@ extern void perf_disable(void);
extern void perf_enable(void);
extern int perf_event_task_disable(void);
extern int perf_event_task_enable(void);
-extern int hw_perf_group_sched_in(struct perf_event *group_leader,
- struct perf_cpu_context *cpuctx,
- struct perf_event_context *ctx);
extern void perf_event_update_userpage(struct perf_event *event);
extern int perf_event_release_kernel(struct perf_event *event);
extern struct perf_event *
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 34659d4..bb06382 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -83,14 +83,6 @@ extern __weak const struct pmu *hw_perf_event_init(struct perf_event *event)
void __weak hw_perf_disable(void) { barrier(); }
void __weak hw_perf_enable(void) { barrier(); }
-int __weak
-hw_perf_group_sched_in(struct perf_event *group_leader,
- struct perf_cpu_context *cpuctx,
- struct perf_event_context *ctx)
-{
- return 0;
-}
-
void __weak perf_event_print_debug(void) { }
static DEFINE_PER_CPU(int, perf_disable_count);
@@ -644,15 +636,20 @@ group_sched_in(struct perf_event *group_event,
struct perf_cpu_context *cpuctx,
struct perf_event_context *ctx)
{
- struct perf_event *event, *partial_group;
+ struct perf_event *event, *partial_group = NULL;
+ const struct pmu *pmu = group_event->pmu;
+ bool txn = false;
int ret;
if (group_event->state == PERF_EVENT_STATE_OFF)
return 0;
- ret = hw_perf_group_sched_in(group_event, cpuctx, ctx);
- if (ret)
- return ret < 0 ? ret : 0;
+ /* Check if group transaction availabe */
+ if (pmu->start_txn)
+ txn = true;
+
+ if (txn)
+ pmu->start_txn(pmu);
if (event_sched_in(group_event, cpuctx, ctx))
return -EAGAIN;
@@ -667,9 +664,19 @@ group_sched_in(struct perf_event *group_event,
}
}
- return 0;
+ if (txn) {
+ ret = pmu->commit_txn(pmu);
+ if (!ret) {
+ pmu->cancel_txn(pmu);
+
+ return 0;
+ }
+ }
group_error:
+ if (txn)
+ pmu->cancel_txn(pmu);
+
/*
* Groups can be scheduled in as one unit only, so undo any
* partial group before returning:
--
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