Re: [PATCH V4 04/10] x86, perf: Add conditional branch filtering support
From: Andi Kleen <hidden>
Date: 2013-12-06 16:46:49
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On Wed, Dec 04, 2013 at 04:02:36PM +0530, Anshuman Khandual wrote:
This patch adds conditional branch filtering support, enabling it for PERF_SAMPLE_BRANCH_COND in perf branch stack sampling framework by utilizing an available software filter X86_BR_JCC.
Newer Intel CPUs a hardware filter too for "not a conditional branch". I can look at implementing that. The software option seems fine for now. -Andi
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Signed-off-by: Anshuman Khandual <redacted> Reviewed-by: Stephane Eranian <redacted> --- arch/x86/kernel/cpu/perf_event_intel_lbr.c | 5 +++++ 1 file changed, 5 insertions(+)diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index d82d155..9dd2459 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c@@ -384,6 +384,9 @@ static void intel_pmu_setup_sw_lbr_filter(struct perf_event *event) if (br_type & PERF_SAMPLE_BRANCH_NO_TX) mask |= X86_BR_NO_TX; + if (br_type & PERF_SAMPLE_BRANCH_COND) + mask |= X86_BR_JCC; + /* * stash actual user request into reg, it may * be used by fixup code for some CPU@@ -678,6 +681,7 @@ static const int nhm_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX] = { * NHM/WSM erratum: must include IND_JMP to capture IND_CALL */ [PERF_SAMPLE_BRANCH_IND_CALL] = LBR_IND_CALL | LBR_IND_JMP, + [PERF_SAMPLE_BRANCH_COND] = LBR_JCC, }; static const int snb_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX] = {@@ -689,6 +693,7 @@ static const int snb_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX] = { [PERF_SAMPLE_BRANCH_ANY_CALL] = LBR_REL_CALL | LBR_IND_CALL | LBR_FAR, [PERF_SAMPLE_BRANCH_IND_CALL] = LBR_IND_CALL, + [PERF_SAMPLE_BRANCH_COND] = LBR_JCC, }; /* core */-- 1.7.11.7
-- ak@linux.intel.com -- Speaking for myself only