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Date: Thu, 3 Dec 2015 12:32:42 +0200
From: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
vince@...ter.net, eranian@...gle.com, johannes@...solutions.net,
Arnaldo Carvalho de Melo <acme@...radead.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Mathieu Poirier <mathieu.poirier@...aro.org>
Subject: [PATCH 7/7] perf/x86/intel/bts: Move transaction start/stop to start/stop callbacks
As per AUX buffer management requirement, AUX output has to happen between
pmu::start and pmu::stop calls so that perf_event_stop() actually stops it
and therefore perf can free the aux data after it has called pmu::stop.
This patch moves perf_aux_output_{begin,end} from bts_event_{add,del} to
bts_event_{start,stop}. As a bonus, we get rid of bts_buffer_is_full(),
which is already taken care of by perf_aux_output_begin() anyway.
Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
---
arch/x86/kernel/cpu/perf_event_intel_bts.c | 105 +++++++++++++----------------
1 file changed, 48 insertions(+), 57 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event_intel_bts.c b/arch/x86/kernel/cpu/perf_event_intel_bts.c
index 2cad71d1b1..5f9c6fbac2 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_bts.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_bts.c
@@ -171,18 +171,6 @@ static void bts_buffer_pad_out(struct bts_phys *phys, unsigned long head)
memset(page_address(phys->page) + index, 0, phys->size - index);
}
-static bool bts_buffer_is_full(struct bts_buffer *buf, struct bts_ctx *bts)
-{
- if (buf->snapshot)
- return false;
-
- if (local_read(&buf->data_size) >= bts->handle.size ||
- bts->handle.size - local_read(&buf->data_size) < BTS_RECORD_SIZE)
- return true;
-
- return false;
-}
-
static void bts_update(struct bts_ctx *bts)
{
int cpu = raw_smp_processor_id();
@@ -213,18 +201,15 @@ static void bts_update(struct bts_ctx *bts)
}
}
+static int
+bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle);
+
static void __bts_event_start(struct perf_event *event)
{
struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
struct bts_buffer *buf = perf_get_aux(&bts->handle);
u64 config = 0;
- if (!buf || bts_buffer_is_full(buf, bts))
- return;
-
- event->hw.itrace_started = 1;
- event->hw.state = 0;
-
if (!buf->snapshot)
config |= ARCH_PERFMON_EVENTSEL_INT;
if (!event->attr.exclude_kernel)
@@ -241,16 +226,41 @@ static void __bts_event_start(struct perf_event *event)
wmb();
intel_pmu_enable_bts(config);
+
}
static void bts_event_start(struct perf_event *event, int flags)
{
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
+ struct bts_buffer *buf;
+
+ buf = perf_aux_output_begin(&bts->handle, event);
+ if (!buf)
+ goto fail_stop;
+
+ if (bts_buffer_reset(buf, &bts->handle))
+ goto fail_end_stop;
+
+ bts->ds_back.bts_buffer_base = cpuc->ds->bts_buffer_base;
+ bts->ds_back.bts_absolute_maximum = cpuc->ds->bts_absolute_maximum;
+ bts->ds_back.bts_interrupt_threshold = cpuc->ds->bts_interrupt_threshold;
+
+ event->hw.itrace_started = 1;
+ event->hw.state = 0;
__bts_event_start(event);
/* PMI handler: this counter is running and likely generating PMIs */
ACCESS_ONCE(bts->started) = 1;
+
+ return;
+
+fail_end_stop:
+ perf_aux_output_end(&bts->handle, 0, false);
+
+fail_stop:
+ event->hw.state = PERF_HES_STOPPED;
}
static void __bts_event_stop(struct perf_event *event)
@@ -269,15 +279,32 @@ static void __bts_event_stop(struct perf_event *event)
static void bts_event_stop(struct perf_event *event, int flags)
{
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
+ struct bts_buffer *buf = perf_get_aux(&bts->handle);
/* PMI handler: don't restart this counter */
ACCESS_ONCE(bts->started) = 0;
__bts_event_stop(event);
- if (flags & PERF_EF_UPDATE)
+ if (flags & PERF_EF_UPDATE) {
bts_update(bts);
+
+ if (buf) {
+ if (buf->snapshot)
+ bts->handle.head =
+ local_xchg(&buf->data_size,
+ buf->nr_pages << PAGE_SHIFT);
+ perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0),
+ !!local_xchg(&buf->lost, 0));
+ }
+
+ cpuc->ds->bts_index = bts->ds_back.bts_buffer_base;
+ cpuc->ds->bts_buffer_base = bts->ds_back.bts_buffer_base;
+ cpuc->ds->bts_absolute_maximum = bts->ds_back.bts_absolute_maximum;
+ cpuc->ds->bts_interrupt_threshold = bts->ds_back.bts_interrupt_threshold;
+ }
}
void intel_bts_enable_local(void)
@@ -417,34 +444,14 @@ int intel_bts_interrupt(void)
static void bts_event_del(struct perf_event *event, int mode)
{
- struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
- struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
- struct bts_buffer *buf = perf_get_aux(&bts->handle);
-
bts_event_stop(event, PERF_EF_UPDATE);
-
- if (buf) {
- if (buf->snapshot)
- bts->handle.head =
- local_xchg(&buf->data_size,
- buf->nr_pages << PAGE_SHIFT);
- perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0),
- !!local_xchg(&buf->lost, 0));
- }
-
- cpuc->ds->bts_index = bts->ds_back.bts_buffer_base;
- cpuc->ds->bts_buffer_base = bts->ds_back.bts_buffer_base;
- cpuc->ds->bts_absolute_maximum = bts->ds_back.bts_absolute_maximum;
- cpuc->ds->bts_interrupt_threshold = bts->ds_back.bts_interrupt_threshold;
}
static int bts_event_add(struct perf_event *event, int mode)
{
- struct bts_buffer *buf;
struct bts_ctx *bts = this_cpu_ptr(&bts_ctx);
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct hw_perf_event *hwc = &event->hw;
- int ret = -EBUSY;
event->hw.state = PERF_HES_STOPPED;
@@ -454,26 +461,10 @@ static int bts_event_add(struct perf_event *event, int mode)
if (bts->handle.event)
return -EBUSY;
- buf = perf_aux_output_begin(&bts->handle, event);
- if (!buf)
- return -EINVAL;
-
- ret = bts_buffer_reset(buf, &bts->handle);
- if (ret) {
- perf_aux_output_end(&bts->handle, 0, false);
- return ret;
- }
-
- bts->ds_back.bts_buffer_base = cpuc->ds->bts_buffer_base;
- bts->ds_back.bts_absolute_maximum = cpuc->ds->bts_absolute_maximum;
- bts->ds_back.bts_interrupt_threshold = cpuc->ds->bts_interrupt_threshold;
-
if (mode & PERF_EF_START) {
bts_event_start(event, 0);
- if (hwc->state & PERF_HES_STOPPED) {
- bts_event_del(event, 0);
- return -EBUSY;
- }
+ if (hwc->state & PERF_HES_STOPPED)
+ return -EINVAL;
}
return 0;
--
2.6.2
--
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