In addition to using the transaction interface to schedule events
on a PMU, we will use it to also read a group of counters at once.
Accordingly, add a flags parameter to the transaction interfaces.
The flags indicate wheether the transaction is to add events to
the PMU (PERF_PMU_TXN_ADD) or to read the events PERF_PMU_TXN_READ.
Based on input from Peter Zijlstra.
Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
---
arch/powerpc/perf/core-book3s.c | 15 ++++++++++++---
arch/x86/kernel/cpu/perf_event.c | 15 ++++++++++++---
include/linux/perf_event.h | 14 +++++++++++---
kernel/events/core.c | 26 +++++++++++++++-----------
4 files changed, 50 insertions(+), 20 deletions(-)
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 7c4f669..3d3739a 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -1573,10 +1573,13 @@ static void power_pmu_stop(struct perf_event *event,
int ef_flags)
* Set the flag to make pmu::enable() not perform the
* schedulability test, it will be performed at commit time
*/
-static void power_pmu_start_txn(struct pmu *pmu)
+static void power_pmu_start_txn(struct pmu *pmu, int flags)
{
struct cpu_hw_events *cpuhw = this_cpu_ptr(&cpu_hw_events);
+ if (flags & ~PERF_PMU_TXN_ADD)
+ return;
+
perf_pmu_disable(pmu);
cpuhw->group_flag |= PERF_EVENT_TXN;
cpuhw->n_txn_start = cpuhw->n_events;
@@ -1587,10 +1590,13 @@ static void power_pmu_start_txn(struct pmu *pmu)
* Clear the flag and pmu::enable() will perform the
* schedulability test.
*/
-static void power_pmu_cancel_txn(struct pmu *pmu)
+static void power_pmu_cancel_txn(struct pmu *pmu, int flags)
{
struct cpu_hw_events *cpuhw = this_cpu_ptr(&cpu_hw_events);
+ if (flags & ~PERF_PMU_TXN_ADD)
+ return;
+
cpuhw->group_flag &= ~PERF_EVENT_TXN;
perf_pmu_enable(pmu);
}
@@ -1600,11 +1606,14 @@ static void power_pmu_cancel_txn(struct pmu *pmu)
* Perform the group schedulability test as a whole
* Return 0 if success
*/
-static int power_pmu_commit_txn(struct pmu *pmu)
+static int power_pmu_commit_txn(struct pmu *pmu, int flags)
{
struct cpu_hw_events *cpuhw;
long i, n;
+ if (flags & ~PERF_PMU_TXN_ADD)
+ return -EINVAL;
+
if (!ppmu)
return -EAGAIN;
cpuhw = this_cpu_ptr(&cpu_hw_events);
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index b71a7f8..b2c9e3b 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1607,8 +1607,11 @@ static inline void x86_pmu_read(struct perf_event *event)
* Set the flag to make pmu::enable() not perform the
* schedulability test, it will be performed at commit time
*/
-static void x86_pmu_start_txn(struct pmu *pmu)
+static void x86_pmu_start_txn(struct pmu *pmu, int flags)
{
+ if (flags & ~PERF_PMU_TXN_ADD)
+ 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);
@@ -1619,8 +1622,11 @@ static void x86_pmu_start_txn(struct pmu *pmu)
* Clear the flag and pmu::enable() will perform the
* schedulability test.
*/
-static void x86_pmu_cancel_txn(struct pmu *pmu)
+static void x86_pmu_cancel_txn(struct pmu *pmu, int flags)
{
+ if (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
@@ -1638,12 +1644,15 @@ static void x86_pmu_cancel_txn(struct pmu *pmu)
*
* Does not cancel the transaction on failure; expects the caller to do this.
*/
-static int x86_pmu_commit_txn(struct pmu *pmu)
+static int x86_pmu_commit_txn(struct pmu *pmu, int flags)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
int assign[X86_PMC_IDX_MAX];
int n, ret;
+ if (flags & ~PERF_PMU_TXN_ADD)
+ return -EINVAL;
+
n = cpuc->n_events;
if (!x86_pmu_initialized())
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2b62198..c8fe60e 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -225,6 +225,8 @@ struct pmu {
* should stop the counter when perf_event_overflow() returns
* !0. ->start() will be used to continue.
*/
+#define PERF_PMU_TXN_ADD 1
+#define PERF_PMU_TXN_READ 2
void (*start) (struct perf_event *event, int flags);
void (*stop) (struct perf_event *event, int flags);
@@ -240,20 +242,26 @@ struct pmu {
*
* Start the transaction, after this ->add() doesn't need to
* do schedulability tests.
+ *
+ * Optional.
*/
- void (*start_txn) (struct pmu *pmu); /* optional */
+ void (*start_txn) (struct pmu *pmu, int flags);
/*
* If ->start_txn() disabled the ->add() 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.
+ *
+ * Optional.
*/
- int (*commit_txn) (struct pmu *pmu); /* optional */
+ int (*commit_txn) (struct pmu *pmu, int flags);
/*
* Will cancel the transaction, assumes ->del() is called
* for each successful ->add() during the transaction.
+ *
+ * Optional.
*/
- void (*cancel_txn) (struct pmu *pmu); /* optional */
+ void (*cancel_txn) (struct pmu *pmu, int flags);
/*
* Will return the value for perf_event_mmap_page::index for this event,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f04daab..dbc12bf 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1924,10 +1924,10 @@ group_sched_in(struct perf_event *group_event,
if (group_event->state == PERF_EVENT_STATE_OFF)
return 0;
- pmu->start_txn(pmu);
+ pmu->start_txn(pmu, PERF_PMU_TXN_ADD);
if (event_sched_in(group_event, cpuctx, ctx)) {
- pmu->cancel_txn(pmu);
+ pmu->cancel_txn(pmu, PERF_PMU_TXN_ADD);
perf_cpu_hrtimer_restart(cpuctx);
return -EAGAIN;
}
@@ -1942,7 +1942,7 @@ group_sched_in(struct perf_event *group_event,
}
}
- if (!pmu->commit_txn(pmu))
+ if (!pmu->commit_txn(pmu, PERF_PMU_TXN_ADD))
return 0;
group_error:
@@ -1973,7 +1973,7 @@ group_error:
}
event_sched_out(group_event, cpuctx, ctx);
- pmu->cancel_txn(pmu);
+ pmu->cancel_txn(pmu, PERF_PMU_TXN_ADD);
perf_cpu_hrtimer_restart(cpuctx);
@@ -6718,23 +6718,27 @@ static void perf_pmu_nop_void(struct pmu *pmu)
{
}
-static int perf_pmu_nop_int(struct pmu *pmu)
+static void perf_pmu_nop_txn(struct pmu *pmu, int flags)
+{
+}
+
+static int perf_pmu_nop_txn_int(struct pmu *pmu, int flags)
{
return 0;
}
-static void perf_pmu_start_txn(struct pmu *pmu)
+static void perf_pmu_start_txn(struct pmu *pmu, int flags)
{
perf_pmu_disable(pmu);
}
-static int perf_pmu_commit_txn(struct pmu *pmu)
+static int perf_pmu_commit_txn(struct pmu *pmu, int flags)
{
perf_pmu_enable(pmu);
return 0;
}
-static void perf_pmu_cancel_txn(struct pmu *pmu)
+static void perf_pmu_cancel_txn(struct pmu *pmu, int flags)
{
perf_pmu_enable(pmu);
}
@@ -6968,9 +6972,9 @@ got_cpu_context:
pmu->commit_txn = perf_pmu_commit_txn;
pmu->cancel_txn = perf_pmu_cancel_txn;
} else {
- pmu->start_txn = perf_pmu_nop_void;
- pmu->commit_txn = perf_pmu_nop_int;
- pmu->cancel_txn = perf_pmu_nop_void;
+ pmu->start_txn = perf_pmu_nop_txn;
+ pmu->commit_txn = perf_pmu_nop_txn_int;
+ pmu->cancel_txn = perf_pmu_nop_txn;
}
}
--
1.8.3.1
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