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Subject[[PATCH v6 10/10] perf: Drop PERF_EVENT_TXN
Date
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>
---
arch/powerpc/perf/core-book3s.c | 6 +-----
arch/s390/kernel/perf_cpum_cf.c | 5 +----
arch/sparc/kernel/perf_event.c | 6 +-----
arch/x86/kernel/cpu/perf_event.c | 7 ++-----
arch/x86/kernel/cpu/perf_event.h | 1 -
include/linux/perf_event.h | 2 --
6 files changed, 5 insertions(+), 22 deletions(-)

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index a9e9a39..b699d19 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -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;

@@ -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))
@@ -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;
}

@@ -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);
}

@@ -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;
diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
index dbcfd29..f50ef65 100644
--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -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;

@@ -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;
}

@@ -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);
}

@@ -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;
diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index 2c0984d..b0da5ae 100644
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -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, };
@@ -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))
@@ -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;
}

/*
@@ -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);
}

@@ -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;
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index dc77ef4..4562cf0 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -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);
@@ -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;

/*
@@ -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);
}

@@ -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().
@@ -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;
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index c99c93b..953a0e4 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -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;

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index b3435e7..8d204d3 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -166,8 +166,6 @@ 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 */

--
1.7.9.5


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