Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH 3/3] perf, x86: Add INST_RETIRED.PREC_DIST workarounds | Date | Tue, 12 Aug 2014 18:45:15 -0700 |
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From: Andi Kleen <ak@linux.intel.com>
On Broadwell INST_RETIRED.PREC_DIST cannot be used with any period that doesn't have the lowest 6 bits cleared. And the period should not be smaller than 128.
Add a new callback to enforce this, and set it for Broadwell.
This is erratum BDM57 and BDM11.
Signed-off-by: Andi Kleen <ak@linux.intel.com> --- arch/x86/kernel/cpu/perf_event.c | 3 +++ arch/x86/kernel/cpu/perf_event.h | 1 + arch/x86/kernel/cpu/perf_event_intel.c | 18 ++++++++++++++++++ 3 files changed, 22 insertions(+)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 0adc5e3..a0adf58 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -980,6 +980,9 @@ int x86_perf_event_set_period(struct perf_event *event) if (left > x86_pmu.max_period) left = x86_pmu.max_period; + if (x86_pmu.limit_period) + left = x86_pmu.limit_period(event, left); + per_cpu(pmc_prev_left[idx], smp_processor_id()) = left; /* diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h index de81627..a46e391 100644 --- a/arch/x86/kernel/cpu/perf_event.h +++ b/arch/x86/kernel/cpu/perf_event.h @@ -456,6 +456,7 @@ struct x86_pmu { struct x86_pmu_quirk *quirks; int perfctr_second_write; bool late_ack; + unsigned (*limit_period)(struct perf_event *event, unsigned l); /* * sysfs attrs diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index dd0ea95..db131b0 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -2034,6 +2034,23 @@ hsw_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event) return c; } +/* + * Broadwell: + * The INST_RETIRED.ALL period always needs to have lowest + * 6bits cleared (BDM57). It shall not use a period smaller + * than 100 (BDM11). We combine the two to enforce + * a min-period of 128. + */ +static unsigned bdw_limit_period(struct perf_event *event, unsigned left) +{ + if ((event->hw.config & 0xffff) == 0x1c0) { + if (left < 128) + left = 128; + left &= ~0x3fu; + } + return left; +} + PMU_FORMAT_ATTR(event, "config:0-7" ); PMU_FORMAT_ATTR(umask, "config:8-15" ); PMU_FORMAT_ATTR(edge, "config:18" ); @@ -2713,6 +2730,7 @@ __init int intel_pmu_init(void) x86_pmu.hw_config = hsw_hw_config; x86_pmu.get_event_constraints = hsw_get_event_constraints; x86_pmu.cpu_events = hsw_events_attrs; + x86_pmu.limit_period = bdw_limit_period; pr_cont("Broadwell events, "); break; -- 1.9.3
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