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perf: Simplify the branch stack check 

Use event->attr.branch_sample_type to replace
intel_pmu_needs_lbr_smpl() for avoiding duplicated code that
implicitly enables the LBR.

Currently, branch stack can be enabled by user explicitly requesting
branch sampling or implicit branch sampling to correct PEBS skid.

For user explicitly requested branch sampling, the branch_sample_type
is explicitly set by user. For PEBS case, the branch_sample_type is also
implicitly set to PERF_SAMPLE_BRANCH_ANY in x86_pmu_hw_config.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: eranian@google.com
Cc: jolsa@redhat.com
Link: http://lkml.kernel.org/r/1415156173-10035-11-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Yan, Zheng 2014-11-04 21:56:06 -05:00 committed by Ingo Molnar
parent 76cb2c617f
commit a46a230001
3 changed files with 11 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
arch/x86/kernel/cpu/perf_event_intel.c
View File

@ -1029,20 +1029,6 @@ static __initconst const u64 slm_hw_cache_event_ids
},
};
static inline bool intel_pmu_needs_lbr_smpl(struct perf_event *event)
{
/* user explicitly requested branch sampling */
if (has_branch_stack(event))
return true;
/* implicit branch sampling to correct PEBS skid */
if (x86_pmu.intel_cap.pebs_trap && event->attr.precise_ip > 1 &&
x86_pmu.intel_cap.pebs_format < 2)
return true;
return false;
}
static void intel_pmu_disable_all(void)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
@ -1207,7 +1193,7 @@ static void intel_pmu_disable_event(struct perf_event *event)
* must disable before any actual event
* because any event may be combined with LBR
*/
if (intel_pmu_needs_lbr_smpl(event))
if (needs_branch_stack(event))
intel_pmu_lbr_disable(event);
if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) {
@ -1268,7 +1254,7 @@ static void intel_pmu_enable_event(struct perf_event *event)
* must enabled before any actual event
* because any event may be combined with LBR
*/
if (intel_pmu_needs_lbr_smpl(event))
if (needs_branch_stack(event))
intel_pmu_lbr_enable(event);
if (event->attr.exclude_host)
@ -1747,7 +1733,7 @@ static int intel_pmu_hw_config(struct perf_event *event)
if (event->attr.precise_ip && x86_pmu.pebs_aliases)
x86_pmu.pebs_aliases(event);
if (intel_pmu_needs_lbr_smpl(event)) {
if (needs_branch_stack(event)) {
ret = intel_pmu_setup_lbr_filter(event);
if (ret)
return ret;

5
include/linux/perf_event.h
View File

@ -814,6 +814,11 @@ static inline bool has_branch_stack(struct perf_event *event)
return event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK;
}
static inline bool needs_branch_stack(struct perf_event *event)
{
return event->attr.branch_sample_type != 0;
}
extern int perf_output_begin(struct perf_output_handle *handle,
struct perf_event *event, unsigned int size);
extern void perf_output_end(struct perf_output_handle *handle);

3
kernel/events/core.c
View File

@ -7232,6 +7232,9 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
goto err_ns;
if (!has_branch_stack(event))
event->attr.branch_sample_type = 0;
pmu = perf_init_event(event);
if (!pmu)
goto err_ns;