Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752134Ab0DUIIB (ORCPT ); Wed, 21 Apr 2010 04:08:01 -0400 Received: from mga09.intel.com ([134.134.136.24]:38211 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751173Ab0DUIH5 (ORCPT ); Wed, 21 Apr 2010 04:07:57 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.52,249,1270450800"; d="scan'208";a="511022705" Subject: Re: [RFC] perf_events: support for uncore a.k.a. nest units From: Lin Ming To: Peter Zijlstra Cc: "Gary.Mohr@Bull.com" , Corey Ashford , Stephane Eranian , LKML In-Reply-To: <1271764993.1676.431.camel@laptop> References: <1271424250.4807.2277.camel@twins> <1271764547.13968.69.camel@minggr.sh.intel.com> <1271764993.1676.431.camel@laptop> Content-Type: text/plain Date: Wed, 21 Apr 2010 16:08:14 +0800 Message-Id: <1271837295.3794.3.camel@minggr.sh.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1 (2.24.1-2.fc10) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10164 Lines: 367 On Tue, 2010-04-20 at 20:03 +0800, Peter Zijlstra wrote: > On Tue, 2010-04-20 at 19:55 +0800, Lin Ming wrote: > > > > One thing not on that list, which should happen first I guess, is to > > > remove hw_perf_group_sched_in(). The idea is to add some sort of > > > transactional API to the struct pmu, so that we can delay the > > > schedulability check until commit time (and roll back when it fails). > > > > > > Something as simple as: > > > > > > struct pmu { > > > void start_txn(struct pmu *); > > > void commit_txn(struct pmu *); > > > > > > ,,, > > > }; > > > > Could you please explain a bit more? > > > > Does it mean that "start_txn" perform the schedule events stuff > > and "commit_txn" perform the assign events stuff? > > > > Does "commit time" mean the actual activation in hw_perf_enable? > > No, the idea behind hw_perf_group_sched_in() is to not perform > schedulability tests on each event in the group, but to add the group as > a whole and then perform one test. > > Of course, when that test fails, you'll have to roll-back the whole > group again. > > So start_txn (or a better name) would simply toggle a flag in the pmu > implementation that will make pmu::enable() not perform the > schedulablilty test. > > Then commit_txn() will perform the schedulability test (so note the > method has to have a !void return value, my mistake in the earlier > email). > > This will allow us to use the regular > kernel/perf_event.c::group_sched_in() and all the rollback code. > Currently each hw_perf_group_sched_in() implementation duplicates all > the rolllback code (with various bugs). > > > > We must get rid of all weak hw_perf_*() functions before we can properly > consider multiple struct pmu implementations. > Thanks for the clear explanation. Does below patch show what you mean? I only touch the x86 arch code now. --- arch/x86/kernel/cpu/perf_event.c | 161 +++++++++++-------------------------- include/linux/perf_event.h | 10 ++- kernel/perf_event.c | 28 +++---- 3 files changed, 67 insertions(+), 132 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 626154a..62aa9a1 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -944,6 +944,9 @@ static int x86_pmu_enable(struct perf_event *event) if (n < 0) return n; + if (!(event->pmu->flag & PERF_EVENT_TRAN_STARTED)) + goto out; + ret = x86_pmu.schedule_events(cpuc, n, assign); if (ret) return ret; @@ -953,6 +956,7 @@ static int x86_pmu_enable(struct perf_event *event) */ memcpy(cpuc->assign, assign, n*sizeof(int)); +out: cpuc->n_events = n; cpuc->n_added += n - n0; @@ -1210,119 +1214,6 @@ x86_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event) return &unconstrained; } -static int x86_event_sched_in(struct perf_event *event, - struct perf_cpu_context *cpuctx) -{ - int ret = 0; - - event->state = PERF_EVENT_STATE_ACTIVE; - event->oncpu = smp_processor_id(); - event->tstamp_running += event->ctx->time - event->tstamp_stopped; - - if (!is_x86_event(event)) - ret = event->pmu->enable(event); - - if (!ret && !is_software_event(event)) - cpuctx->active_oncpu++; - - if (!ret && event->attr.exclusive) - cpuctx->exclusive = 1; - - return ret; -} - -static void x86_event_sched_out(struct perf_event *event, - struct perf_cpu_context *cpuctx) -{ - event->state = PERF_EVENT_STATE_INACTIVE; - event->oncpu = -1; - - if (!is_x86_event(event)) - event->pmu->disable(event); - - event->tstamp_running -= event->ctx->time - event->tstamp_stopped; - - if (!is_software_event(event)) - cpuctx->active_oncpu--; - - if (event->attr.exclusive || !cpuctx->active_oncpu) - cpuctx->exclusive = 0; -} - -/* - * Called to enable a whole group of events. - * Returns 1 if the group was enabled, or -EAGAIN if it could not be. - * Assumes the caller has disabled interrupts and has - * frozen the PMU with hw_perf_save_disable. - * - * called with PMU disabled. If successful and return value 1, - * then guaranteed to call perf_enable() and hw_perf_enable() - */ -int hw_perf_group_sched_in(struct perf_event *leader, - struct perf_cpu_context *cpuctx, - struct perf_event_context *ctx) -{ - struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); - struct perf_event *sub; - int assign[X86_PMC_IDX_MAX]; - int n0, n1, ret; - - if (!x86_pmu_initialized()) - return 0; - - /* n0 = total number of events */ - n0 = collect_events(cpuc, leader, true); - if (n0 < 0) - return n0; - - ret = x86_pmu.schedule_events(cpuc, n0, assign); - if (ret) - return ret; - - ret = x86_event_sched_in(leader, cpuctx); - if (ret) - return ret; - - n1 = 1; - list_for_each_entry(sub, &leader->sibling_list, group_entry) { - if (sub->state > PERF_EVENT_STATE_OFF) { - ret = x86_event_sched_in(sub, cpuctx); - if (ret) - goto undo; - ++n1; - } - } - /* - * copy new assignment, now we know it is possible - * will be used by hw_perf_enable() - */ - memcpy(cpuc->assign, assign, n0*sizeof(int)); - - cpuc->n_events = n0; - cpuc->n_added += n1; - ctx->nr_active += n1; - - /* - * 1 means successful and events are active - * This is not quite true because we defer - * actual activation until hw_perf_enable() but - * this way we* ensure caller won't try to enable - * individual events - */ - return 1; -undo: - x86_event_sched_out(leader, cpuctx); - n0 = 1; - list_for_each_entry(sub, &leader->sibling_list, group_entry) { - if (sub->state == PERF_EVENT_STATE_ACTIVE) { - x86_event_sched_out(sub, cpuctx); - if (++n0 == n1) - break; - } - } - return ret; -} - #include "perf_event_amd.c" #include "perf_event_p6.c" #include "perf_event_p4.c" @@ -1454,6 +1345,47 @@ static inline void x86_pmu_read(struct perf_event *event) x86_perf_event_update(event); } +/* + * Set the flag to make pmu::enable() not perform the + * schedulablilty test. + */ +static void x86_pmu_start_txn(struct pmu *pmu) +{ + pmu->flag |= PERF_EVENT_TRAN_STARTED; +} + +static void x86_pmu_stop_txn(struct pmu *pmu) +{ + pmu->flag &= ~PERF_EVENT_TRAN_STARTED; +} + +/* + * Return 0 if commit transaction success + */ +static int x86_pmu_commit_txn(struct pmu *pmu) +{ + struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); + int assign[X86_PMC_IDX_MAX]; + int n, ret; + + n = cpuc->n_events; + + if (!x86_pmu_initialized()) + return -EAGAIN; + + ret = x86_pmu.schedule_events(cpuc, n, assign); + if (ret) + return ret; + + /* + * copy new assignment, now we know it is possible + * will be used by hw_perf_enable() + */ + memcpy(cpuc->assign, assign, n*sizeof(int)); + + return 0; +} + static const struct pmu pmu = { .enable = x86_pmu_enable, .disable = x86_pmu_disable, @@ -1461,6 +1393,9 @@ static const struct pmu pmu = { .stop = x86_pmu_stop, .read = x86_pmu_read, .unthrottle = x86_pmu_unthrottle, + .start_txn = x86_pmu_start_txn, + .stop_txn = x86_pmu_stop_txn, + .commit_txn = x86_pmu_commit_txn, }; /* diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index bf896d0..93aa8d8 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -524,6 +524,8 @@ struct hw_perf_event { struct perf_event; +#define PERF_EVENT_TRAN_STARTED 1 + /** * struct pmu - generic performance monitoring unit */ @@ -534,6 +536,11 @@ struct pmu { void (*stop) (struct perf_event *event); void (*read) (struct perf_event *event); void (*unthrottle) (struct perf_event *event); + void (*start_txn) (struct pmu *pmu); + void (*stop_txn) (struct pmu *pmu); + int (*commit_txn) (struct pmu *pmu); + + u8 flag; }; /** @@ -799,9 +806,6 @@ extern void perf_disable(void); extern void perf_enable(void); extern int perf_event_task_disable(void); extern int perf_event_task_enable(void); -extern int hw_perf_group_sched_in(struct perf_event *group_leader, - struct perf_cpu_context *cpuctx, - struct perf_event_context *ctx); extern void perf_event_update_userpage(struct perf_event *event); extern int perf_event_release_kernel(struct perf_event *event); extern struct perf_event * diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 07b7a43..4537676 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -83,14 +83,6 @@ extern __weak const struct pmu *hw_perf_event_init(struct perf_event *event) void __weak hw_perf_disable(void) { barrier(); } void __weak hw_perf_enable(void) { barrier(); } -int __weak -hw_perf_group_sched_in(struct perf_event *group_leader, - struct perf_cpu_context *cpuctx, - struct perf_event_context *ctx) -{ - return 0; -} - void __weak perf_event_print_debug(void) { } static DEFINE_PER_CPU(int, perf_disable_count); @@ -642,14 +634,13 @@ group_sched_in(struct perf_event *group_event, struct perf_event_context *ctx) { struct perf_event *event, *partial_group; + struct pmu *pmu = (struct pmu *)group_event->pmu; int ret; if (group_event->state == PERF_EVENT_STATE_OFF) return 0; - ret = hw_perf_group_sched_in(group_event, cpuctx, ctx); - if (ret) - return ret < 0 ? ret : 0; + pmu->start_txn(pmu); if (event_sched_in(group_event, cpuctx, ctx)) return -EAGAIN; @@ -664,16 +655,21 @@ group_sched_in(struct perf_event *group_event, } } - return 0; + ret = pmu->commit_txn(pmu); + if (!ret) { + pmu->stop_txn(pmu); + return 0; + } group_error: + pmu->stop_txn(pmu); + /* - * Groups can be scheduled in as one unit only, so undo any - * partial group before returning: + * Commit transaction fails, rollback + * Groups can be scheduled in as one unit only, so undo + * whole group before returning: */ list_for_each_entry(event, &group_event->sibling_list, group_entry) { - if (event == partial_group) - break; event_sched_out(event, cpuctx, ctx); } event_sched_out(group_event, cpuctx, ctx); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/