Commit-ID: eafade90e67a9b627aee331a9d0cc0c4328fb00e Gitweb: http://git.kernel.org/tip/eafade90e67a9b627aee331a9d0cc0c4328fb00e Author: Stephane Eranian <[email protected]> AuthorDate: Tue, 12 Nov 2013 17:58:51 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Wed, 27 Nov 2013 13:45:04 +0100
perf/x86: Add RAPL hrtimer support The RAPL PMU counters do not interrupt on overflow. Therefore, the kernel needs to poll the counters to avoid missing an overflow. This patch adds the hrtimer code to do this. The timer interval is calculated at boot time based on the power unit used by the HW. There is one hrtimer per-cpu to handle the case of multiple simultaneous use across cores on the same package + hotplug CPU. Signed-off-by: Stephane Eranian <[email protected]> Reviewed-by: Andi Kleen <[email protected]> [ Applied 32-bit build fix. ] Signed-off-by: Peter Zijlstra <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/kernel/cpu/perf_event_intel_rapl.c | 74 ++++++++++++++++++++++++++++- 1 file changed, 72 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_rapl.c b/arch/x86/kernel/cpu/perf_event_intel_rapl.c index cfcd386..bf8e4a7 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_rapl.c +++ b/arch/x86/kernel/cpu/perf_event_intel_rapl.c @@ -96,6 +96,8 @@ struct rapl_pmu { int n_active; /* number of active events */ struct list_head active_list; struct pmu *pmu; /* pointer to rapl_pmu_class */ + ktime_t timer_interval; /* in ktime_t unit */ + struct hrtimer hrtimer; }; static struct pmu rapl_pmu_class; @@ -158,6 +160,48 @@ again: return new_raw_count; } +static void rapl_start_hrtimer(struct rapl_pmu *pmu) +{ + __hrtimer_start_range_ns(&pmu->hrtimer, + pmu->timer_interval, 0, + HRTIMER_MODE_REL_PINNED, 0); +} + +static void rapl_stop_hrtimer(struct rapl_pmu *pmu) +{ + hrtimer_cancel(&pmu->hrtimer); +} + +static enum hrtimer_restart rapl_hrtimer_handle(struct hrtimer *hrtimer) +{ + struct rapl_pmu *pmu = __get_cpu_var(rapl_pmu); + struct perf_event *event; + unsigned long flags; + + if (!pmu->n_active) + return HRTIMER_NORESTART; + + spin_lock_irqsave(&pmu->lock, flags); + + list_for_each_entry(event, &pmu->active_list, active_entry) { + rapl_event_update(event); + } + + spin_unlock_irqrestore(&pmu->lock, flags); + + hrtimer_forward_now(hrtimer, pmu->timer_interval); + + return HRTIMER_RESTART; +} + +static void rapl_hrtimer_init(struct rapl_pmu *pmu) +{ + struct hrtimer *hr = &pmu->hrtimer; + + hrtimer_init(hr, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + hr->function = rapl_hrtimer_handle; +} + static void __rapl_pmu_event_start(struct rapl_pmu *pmu, struct perf_event *event) { @@ -171,6 +215,8 @@ static void __rapl_pmu_event_start(struct rapl_pmu *pmu, local64_set(&event->hw.prev_count, rapl_read_counter(event)); pmu->n_active++; + if (pmu->n_active == 1) + rapl_start_hrtimer(pmu); } static void rapl_pmu_event_start(struct perf_event *event, int mode) @@ -195,6 +241,8 @@ static void rapl_pmu_event_stop(struct perf_event *event, int mode) if (!(hwc->state & PERF_HES_STOPPED)) { WARN_ON_ONCE(pmu->n_active <= 0); pmu->n_active--; + if (pmu->n_active == 0) + rapl_stop_hrtimer(pmu); list_del(&event->active_entry); @@ -423,6 +471,9 @@ static void rapl_cpu_exit(int cpu) */ if (target >= 0) perf_pmu_migrate_context(pmu->pmu, cpu, target); + + /* cancel overflow polling timer for CPU */ + rapl_stop_hrtimer(pmu); } static void rapl_cpu_init(int cpu) @@ -442,6 +493,7 @@ static int rapl_cpu_prepare(int cpu) { struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu); int phys_id = topology_physical_package_id(cpu); + u64 ms; if (pmu) return 0; @@ -466,6 +518,22 @@ static int rapl_cpu_prepare(int cpu) pmu->hw_unit = (pmu->hw_unit >> 8) & 0x1FULL; pmu->pmu = &rapl_pmu_class; + /* + * use reference of 200W for scaling the timeout + * to avoid missing counter overflows. + * 200W = 200 Joules/sec + * divide interval by 2 to avoid lockstep (2 * 100) + * if hw unit is 32, then we use 2 ms 1/200/2 + */ + if (pmu->hw_unit < 32) + ms = (1000 / (2 * 100)) * (1ULL << (32 - pmu->hw_unit - 1)); + else + ms = 2; + + pmu->timer_interval = ms_to_ktime(ms); + + rapl_hrtimer_init(pmu); + /* set RAPL pmu for this cpu for now */ per_cpu(rapl_pmu, cpu) = pmu; per_cpu(rapl_pmu_to_free, cpu) = NULL; @@ -580,9 +648,11 @@ static int __init rapl_pmu_init(void) pr_info("RAPL PMU detected, hw unit 2^-%d Joules," " API unit is 2^-32 Joules," - " %d fixed counters\n", + " %d fixed counters" + " %llu ms ovfl timer\n", pmu->hw_unit, - hweight32(rapl_cntr_mask)); + hweight32(rapl_cntr_mask), + ktime_to_ms(pmu->timer_interval)); put_online_cpus(); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
