From 4defea8559bc0f97a899d94c8d19d3b8bb802bc4 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 10 Nov 2011 15:15:42 +0100 Subject: [PATCH] perf, x86: Prefer fixed-purpose counters when scheduling This avoids a scheduling failure for cases like: cycles, cycles, instructions, instructions (on Core2) Which would end up being programmed like: PMC0, PMC1, FP-instructions, fail Because all events will have the same weight. Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-8tnwb92asqj7xajqqoty4gel@git.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index fa6fdec5afbc..66f8ba9a67f9 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -574,16 +574,25 @@ static bool __perf_sched_find_counter(struct perf_sched *sched) c = sched->constraints[sched->state.event]; + /* Prefer fixed purpose counters */ + if (x86_pmu.num_counters_fixed) { + idx = X86_PMC_IDX_FIXED; + for_each_set_bit_cont(idx, c->idxmsk, X86_PMC_IDX_MAX) { + if (!__test_and_set_bit(idx, sched->state.used)) + goto done; + } + } /* Grab the first unused counter starting with idx */ idx = sched->state.counter; - for_each_set_bit_cont(idx, c->idxmsk, X86_PMC_IDX_MAX) { + for_each_set_bit_cont(idx, c->idxmsk, X86_PMC_IDX_FIXED) { if (!__test_and_set_bit(idx, sched->state.used)) - break; + goto done; } - sched->state.counter = idx; - if (idx >= X86_PMC_IDX_MAX) - return false; + return false; + +done: + sched->state.counter = idx; if (c->overlap) perf_sched_save_state(sched); -- 2.20.1