[tip:perf/core] perf/x86/intel/bts: Move transaction start/stop to start/stop callbacks

tip-bot for Alexander Shishkin
2016-03-31T09:26:15Z

Commit-ID: 981a4cb380d3dff7010ce9f89618064a254eab8c
Gitweb: http://git.kernel.org/tip/981a4cb380d3dff7010ce9f89618064a254eab8c
Author: Alexander Shishkin <alexander.shishkin@linux.intel.com>
AuthorDate: Fri, 4 Mar 2016 15:42:49 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 31 Mar 2016 10:30:44 +0200

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@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
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>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/1457098969-21595-6-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/events/intel/bts.c | 105 ++++++++++++++++++++------------------------
1 file changed, 48 insertions(+), 57 deletions(-)

diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index b99dc92..0a6e393 100644
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/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;