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perf/core: Drop PERF_EVENT_TXN
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We currently use PERF_EVENT_TXN flag to determine if we are in the middle
of a transaction. If in a transaction, we defer the schedulability checks
from pmu->add() operation to the pmu->commit() operation.

Now that we have "transaction types" (PERF_PMU_TXN_ADD, PERF_PMU_TXN_READ)
we can use the type to determine if we are in a transaction and drop the
PERF_EVENT_TXN flag.

When PERF_EVENT_TXN is dropped, the cpuhw->group_flag on some architectures
becomes unused, so drop that field as well.

This is an extension of the Powerpc patch from Peter Zijlstra to s390,
Sparc and x86 architectures.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
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>
Link: http://lkml.kernel.org/r/1441336073-22750-11-git-send-email-sukadev@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Sukadev Bhattiprolu authored and Ingo Molnar committed Sep 13, 2015
1 parent 88a4861 commit 8f3e568
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Showing 6 changed files with 5 additions and 22 deletions.
6 changes: 1 addition & 5 deletions arch/powerpc/perf/core-book3s.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,6 @@ struct cpu_hw_events {
unsigned long amasks[MAX_HWEVENTS][MAX_EVENT_ALTERNATIVES];
unsigned long avalues[MAX_HWEVENTS][MAX_EVENT_ALTERNATIVES];

unsigned int group_flag;
unsigned int txn_flags;
int n_txn_start;

Expand Down Expand Up @@ -1442,7 +1441,7 @@ static int power_pmu_add(struct perf_event *event, int ef_flags)
* skip the schedulability test here, it will be performed
* at commit time(->commit_txn) as a whole
*/
if (cpuhw->group_flag & PERF_EVENT_TXN)
if (cpuhw->txn_flags & PERF_PMU_TXN_ADD)
goto nocheck;

if (check_excludes(cpuhw->event, cpuhw->flags, n0, 1))
Expand Down Expand Up @@ -1603,7 +1602,6 @@ static void power_pmu_start_txn(struct pmu *pmu, unsigned int txn_flags)
return;

perf_pmu_disable(pmu);
cpuhw->group_flag |= PERF_EVENT_TXN;
cpuhw->n_txn_start = cpuhw->n_events;
}

Expand All @@ -1624,7 +1622,6 @@ static void power_pmu_cancel_txn(struct pmu *pmu)
if (txn_flags & ~PERF_PMU_TXN_ADD)
return;

cpuhw->group_flag &= ~PERF_EVENT_TXN;
perf_pmu_enable(pmu);
}

Expand Down Expand Up @@ -1659,7 +1656,6 @@ static int power_pmu_commit_txn(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;
cpuhw->txn_flags = 0;
perf_pmu_enable(pmu);
return 0;
Expand Down
5 changes: 1 addition & 4 deletions arch/s390/kernel/perf_cpum_cf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -536,7 +536,7 @@ static int cpumf_pmu_add(struct perf_event *event, int flags)
* For group events transaction, the authorization check is
* done in cpumf_pmu_commit_txn().
*/
if (!(cpuhw->flags & PERF_EVENT_TXN))
if (!(cpuhw->txn_flags & PERF_PMU_TXN_ADD))
if (validate_ctr_auth(&event->hw))
return -EPERM;

Expand Down Expand Up @@ -590,7 +590,6 @@ static void cpumf_pmu_start_txn(struct pmu *pmu, unsigned int txn_flags)
return;

perf_pmu_disable(pmu);
cpuhw->flags |= PERF_EVENT_TXN;
cpuhw->tx_state = cpuhw->state;
}

Expand All @@ -613,7 +612,6 @@ static void cpumf_pmu_cancel_txn(struct pmu *pmu)

WARN_ON(cpuhw->tx_state != cpuhw->state);

cpuhw->flags &= ~PERF_EVENT_TXN;
perf_pmu_enable(pmu);
}

Expand All @@ -640,7 +638,6 @@ static int cpumf_pmu_commit_txn(struct pmu *pmu)
if ((state & cpuhw->info.auth_ctl) != state)
return -EPERM;

cpuhw->flags &= ~PERF_EVENT_TXN;
cpuhw->txn_flags = 0;
perf_pmu_enable(pmu);
return 0;
Expand Down
6 changes: 1 addition & 5 deletions arch/sparc/kernel/perf_event.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -108,7 +108,6 @@ struct cpu_hw_events {
/* Enabled/disable state. */
int enabled;

unsigned int group_flag;
unsigned int txn_flags;
};
static DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = { .enabled = 1, };
Expand Down Expand Up @@ -1380,7 +1379,7 @@ static int sparc_pmu_add(struct perf_event *event, int ef_flags)
* skip the schedulability test here, it will be performed
* at commit time(->commit_txn) as a whole
*/
if (cpuc->group_flag & PERF_EVENT_TXN)
if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
goto nocheck;

if (check_excludes(cpuc->event, n0, 1))
Expand Down Expand Up @@ -1506,7 +1505,6 @@ static void sparc_pmu_start_txn(struct pmu *pmu, unsigned int txn_flags)
return;

perf_pmu_disable(pmu);
cpuhw->group_flag |= PERF_EVENT_TXN;
}

/*
Expand All @@ -1526,7 +1524,6 @@ static void sparc_pmu_cancel_txn(struct pmu *pmu)
if (txn_flags & ~PERF_PMU_TXN_ADD)
return;

cpuhw->group_flag &= ~PERF_EVENT_TXN;
perf_pmu_enable(pmu);
}

Expand Down Expand Up @@ -1556,7 +1553,6 @@ static int sparc_pmu_commit_txn(struct pmu *pmu)
if (sparc_check_constraints(cpuc->event, cpuc->events, n))
return -EAGAIN;

cpuc->group_flag &= ~PERF_EVENT_TXN;
cpuc->txn_flags = 0;
perf_pmu_enable(pmu);
return 0;
Expand Down
7 changes: 2 additions & 5 deletions arch/x86/kernel/cpu/perf_event.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1175,7 +1175,7 @@ static int x86_pmu_add(struct perf_event *event, int flags)
* skip the schedulability test here, it will be performed
* at commit time (->commit_txn) as a whole.
*/
if (cpuc->group_flag & PERF_EVENT_TXN)
if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
goto done_collect;

ret = x86_pmu.schedule_events(cpuc, n, assign);
Expand Down Expand Up @@ -1326,7 +1326,7 @@ static void x86_pmu_del(struct perf_event *event, int flags)
* XXX assumes any ->del() called during a TXN will only be on
* an event added during that same TXN.
*/
if (cpuc->group_flag & PERF_EVENT_TXN)
if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
return;

/*
Expand Down Expand Up @@ -1764,7 +1764,6 @@ static void x86_pmu_start_txn(struct pmu *pmu, unsigned int txn_flags)
return;

perf_pmu_disable(pmu);
__this_cpu_or(cpu_hw_events.group_flag, PERF_EVENT_TXN);
__this_cpu_write(cpu_hw_events.n_txn, 0);
}

Expand All @@ -1785,7 +1784,6 @@ static void x86_pmu_cancel_txn(struct pmu *pmu)
if (txn_flags & ~PERF_PMU_TXN_ADD)
return;

__this_cpu_and(cpu_hw_events.group_flag, ~PERF_EVENT_TXN);
/*
* Truncate collected array by the number of events added in this
* transaction. See x86_pmu_add() and x86_pmu_*_txn().
Expand Down Expand Up @@ -1830,7 +1828,6 @@ static int x86_pmu_commit_txn(struct pmu *pmu)
*/
memcpy(cpuc->assign, assign, n*sizeof(int));

cpuc->group_flag &= ~PERF_EVENT_TXN;
cpuc->txn_flags = 0;
perf_pmu_enable(pmu);
return 0;
Expand Down
1 change: 0 additions & 1 deletion arch/x86/kernel/cpu/perf_event.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -195,7 +195,6 @@ struct cpu_hw_events {

int n_excl; /* the number of exclusive events */

unsigned int group_flag;
unsigned int txn_flags;
int is_fake;

Expand Down
2 changes: 0 additions & 2 deletions include/linux/perf_event.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -199,8 +199,6 @@ struct perf_event;
/*
* Common implementation detail of pmu::{start,commit,cancel}_txn
*/
#define PERF_EVENT_TXN 0x1

#define PERF_PMU_TXN_ADD 0x1 /* txn to add/schedule event on PMU */
#define PERF_PMU_TXN_READ 0x2 /* txn to read event group from PMU */

Expand Down

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