From c090cb70c6152fc97ce91242789d7c322109f1a1 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 14 Mar 2019 13:01:14 +0100 Subject: [PATCH] perf/x86/intel: Optimize intel_get_excl_constraints() Avoid the POPCNT by noting we can decrement the weight for each cleared bit. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Stephane Eranian Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vince Weaver Signed-off-by: Ingo Molnar --- arch/x86/events/intel/core.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 879ab54..a80015f 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -2838,7 +2838,7 @@ intel_get_excl_constraints(struct cpu_hw_events *cpuc, struct perf_event *event, struct intel_excl_cntrs *excl_cntrs = cpuc->excl_cntrs; struct intel_excl_states *xlo; int tid = cpuc->excl_thread_id; - int is_excl, i; + int is_excl, i, w; /* * validating a group does not require @@ -2894,36 +2894,40 @@ intel_get_excl_constraints(struct cpu_hw_events *cpuc, struct perf_event *event, * SHARED : sibling counter measuring non-exclusive event * UNUSED : sibling counter unused */ + w = c->weight; for_each_set_bit(i, c->idxmsk, X86_PMC_IDX_MAX) { /* * exclusive event in sibling counter * our corresponding counter cannot be used * regardless of our event */ - if (xlo->state[i] == INTEL_EXCL_EXCLUSIVE) + if (xlo->state[i] == INTEL_EXCL_EXCLUSIVE) { __clear_bit(i, c->idxmsk); + w--; + continue; + } /* * if measuring an exclusive event, sibling * measuring non-exclusive, then counter cannot * be used */ - if (is_excl && xlo->state[i] == INTEL_EXCL_SHARED) + if (is_excl && xlo->state[i] == INTEL_EXCL_SHARED) { __clear_bit(i, c->idxmsk); + w--; + continue; + } } /* - * recompute actual bit weight for scheduling algorithm - */ - c->weight = hweight64(c->idxmsk64); - - /* * if we return an empty mask, then switch * back to static empty constraint to avoid * the cost of freeing later on */ - if (c->weight == 0) + if (!w) c = &emptyconstraint; + c->weight = w; + return c; } -- 2.7.4