Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 8d2cacbb authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf: Cleanup {start,commit,cancel}_txn details 



Clarify some of the transactional group scheduling API details
and change it so that a successfull ->commit_txn also closes
the transaction.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1274803086.5882.1752.camel@twins>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 3af9e859

arch/powerpc/kernel/perf_event.c

+4 −3
Original line number Diff line number Diff line
@@ -754,7 +754,7 @@ static int power_pmu_enable(struct perf_event *event) 
	 * skip the schedulability test here, it will be peformed

	 * at commit time(->commit_txn) as a whole

	 */

	if (cpuhw->group_flag & PERF_EVENT_TXN_STARTED)

	if (cpuhw->group_flag & PERF_EVENT_TXN)

		goto nocheck;



	if (check_excludes(cpuhw->event, cpuhw->flags, n0, 1))
@@ -858,7 +858,7 @@ void power_pmu_start_txn(const struct pmu *pmu) 
{

	struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);



	cpuhw->group_flag |= PERF_EVENT_TXN_STARTED;

	cpuhw->group_flag |= PERF_EVENT_TXN;

	cpuhw->n_txn_start = cpuhw->n_events;

}
@@ -871,7 +871,7 @@ void power_pmu_cancel_txn(const struct pmu *pmu) 
{

	struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);



	cpuhw->group_flag &= ~PERF_EVENT_TXN_STARTED;

	cpuhw->group_flag &= ~PERF_EVENT_TXN;

}



/*
@@ -897,6 +897,7 @@ int power_pmu_commit_txn(const struct pmu *pmu) 
	for (i = cpuhw->n_txn_start; i < n; ++i)

		cpuhw->event[i]->hw.config = cpuhw->events[i];



	cpuhw->group_flag &= ~PERF_EVENT_TXN;

	return 0;

}

arch/sparc/kernel/perf_event.c

+4 −3
Original line number Diff line number Diff line
@@ -1005,7 +1005,7 @@ static int sparc_pmu_enable(struct perf_event *event) 
	 * skip the schedulability test here, it will be peformed

	 * at commit time(->commit_txn) as a whole

	 */

	if (cpuc->group_flag & PERF_EVENT_TXN_STARTED)

	if (cpuc->group_flag & PERF_EVENT_TXN)

		goto nocheck;



	if (check_excludes(cpuc->event, n0, 1))
@@ -1102,7 +1102,7 @@ static void sparc_pmu_start_txn(const struct pmu *pmu) 
{

	struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);



	cpuhw->group_flag |= PERF_EVENT_TXN_STARTED;

	cpuhw->group_flag |= PERF_EVENT_TXN;

}



/*
@@ -1114,7 +1114,7 @@ static void sparc_pmu_cancel_txn(const struct pmu *pmu) 
{

	struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);



	cpuhw->group_flag &= ~PERF_EVENT_TXN_STARTED;

	cpuhw->group_flag &= ~PERF_EVENT_TXN;

}



/*
@@ -1137,6 +1137,7 @@ static int sparc_pmu_commit_txn(const struct pmu *pmu) 
	if (sparc_check_constraints(cpuc->event, cpuc->events, n))

		return -EAGAIN;



	cpuc->group_flag &= ~PERF_EVENT_TXN;

	return 0;

}

arch/x86/kernel/cpu/perf_event.c

+5 −9
Original line number Diff line number Diff line
@@ -969,7 +969,7 @@ static int x86_pmu_enable(struct perf_event *event) 
	 * skip the schedulability test here, it will be peformed

	 * at commit time(->commit_txn) as a whole

	 */

	if (cpuc->group_flag & PERF_EVENT_TXN_STARTED)

	if (cpuc->group_flag & PERF_EVENT_TXN)

		goto out;



	ret = x86_pmu.schedule_events(cpuc, n, assign);
@@ -1096,7 +1096,7 @@ static void x86_pmu_disable(struct perf_event *event) 
	 * The events never got scheduled and ->cancel_txn will truncate

	 * the event_list.

	 */

	if (cpuc->group_flag & PERF_EVENT_TXN_STARTED)

	if (cpuc->group_flag & PERF_EVENT_TXN)

		return;



	x86_pmu_stop(event);
@@ -1388,7 +1388,7 @@ static void x86_pmu_start_txn(const struct pmu *pmu) 
{

	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);



	cpuc->group_flag |= PERF_EVENT_TXN_STARTED;

	cpuc->group_flag |= PERF_EVENT_TXN;

	cpuc->n_txn = 0;

}
@@ -1401,7 +1401,7 @@ static void x86_pmu_cancel_txn(const struct pmu *pmu) 
{

	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);



	cpuc->group_flag &= ~PERF_EVENT_TXN_STARTED;

	cpuc->group_flag &= ~PERF_EVENT_TXN;

	/*

	 * Truncate the collected events.

	 */
@@ -1435,11 +1435,7 @@ static int x86_pmu_commit_txn(const struct pmu *pmu) 
	 */

	memcpy(cpuc->assign, assign, n*sizeof(int));



	/*

	 * Clear out the txn count so that ->cancel_txn() which gets

	 * run after ->commit_txn() doesn't undo things.

	 */

	cpuc->n_txn = 0;

	cpuc->group_flag &= ~PERF_EVENT_TXN;



	return 0;

}

include/linux/perf_event.h

+22 −5
Original line number Diff line number Diff line
@@ -549,7 +549,10 @@ struct hw_perf_event { 


struct perf_event;



#define PERF_EVENT_TXN_STARTED 1

/*

 * Common implementation detail of pmu::{start,commit,cancel}_txn

 */

#define PERF_EVENT_TXN 0x1



/**

 * struct pmu - generic performance monitoring unit
@@ -563,14 +566,28 @@ struct pmu { 
	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

	 * Group events scheduling is treated as a transaction, add group

	 * events as a whole and perform one schedulability test. If the test

	 * fails, roll back the whole group

	 */



	/*

	 * Start the transaction, after this ->enable() doesn't need

	 * to do schedulability tests.

	 */

	void (*start_txn)	(const struct pmu *pmu);

	void (*cancel_txn)	(const struct pmu *pmu);

	/*

	 * If ->start_txn() disabled the ->enable() schedulability test

	 * then ->commit_txn() is required to perform one. On success

	 * the transaction is closed. On error the transaction is kept

	 * open until ->cancel_txn() is called.

	 */

	int  (*commit_txn)	(const struct pmu *pmu);

	/*

	 * Will cancel the transaction, assumes ->disable() is called for

	 * each successfull ->enable() during the transaction.

	 */

	void (*cancel_txn)	(const struct pmu *pmu);

};



/**

kernel/perf_event.c

+1 −8
Original line number Diff line number Diff line
@@ -675,7 +675,6 @@ group_sched_in(struct perf_event *group_event, 
	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;
@@ -703,15 +702,9 @@ group_sched_in(struct perf_event *group_event, 
		}

	}



	if (!txn)

	if (!txn || !pmu->commit_txn(pmu))

		return 0;



	ret = pmu->commit_txn(pmu);

	if (!ret) {

		pmu->cancel_txn(pmu);

		return 0;

	}



group_error:

	/*

	 * Groups can be scheduled in as one unit only, so undo any