From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e38.co.us.ibm.com (e38.co.us.ibm.com [32.97.110.159]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 09F721A1D3F for ; Fri, 4 Sep 2015 13:09:47 +1000 (AEST) Received: from /spool/local by e38.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 3 Sep 2015 21:09:46 -0600 Received: from b03cxnp08026.gho.boulder.ibm.com (b03cxnp08026.gho.boulder.ibm.com [9.17.130.18]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id AB5A119D8041 for ; Thu, 3 Sep 2015 21:00:38 -0600 (MDT) Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t8438vCm49021032 for ; Thu, 3 Sep 2015 20:08:57 -0700 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t8439h6Q005139 for ; Thu, 3 Sep 2015 21:09:43 -0600 From: Sukadev Bhattiprolu To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Michael Ellerman Cc: , linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org Subject: [[PATCH v6 08/10] Define PERF_PMU_TXN_READ interface Date: Thu, 3 Sep 2015 20:07:51 -0700 Message-Id: <1441336073-22750-9-git-send-email-sukadev@linux.vnet.ibm.com> In-Reply-To: <1441336073-22750-1-git-send-email-sukadev@linux.vnet.ibm.com> References: <1441336073-22750-1-git-send-email-sukadev@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Define a new PERF_PMU_TXN_READ interface to read a group of counters at once. pmu->start_txn() // Initialize before first event for each event in group pmu->read(event); // Queue each event to be read rc = pmu->commit_txn() // Read/update all queued counters Note that we use this interface with all PMUs. PMUs that implement this interface use the ->read() operation to _queue_ the counters to be read and use ->commit_txn() to actually read all the queued counters at once. PMUs that don't implement PERF_PMU_TXN_READ ignore ->start_txn() and ->commit_txn() and continue to read counters one at a time. Thanks to input from Peter Zijlstra. Signed-off-by: Sukadev Bhattiprolu --- Changelog[v4] - [Peter Zijlstra] Add lockdep_assert_held() in perf_event_read_group(). Make sure the entire transaction happens on the same CPU. --- include/linux/perf_event.h | 1 + kernel/events/core.c | 24 +++++++++++++++++++----- 2 files changed, 20 insertions(+), 5 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 4e8d780..b3435e7 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -169,6 +169,7 @@ struct perf_event; #define PERF_EVENT_TXN 0x1 #define PERF_PMU_TXN_ADD 0x1 /* txn to add/schedule event on PMU */ +#define PERF_PMU_TXN_READ 0x2 /* txn to read event group from PMU */ /** * pmu::capabilities flags diff --git a/kernel/events/core.c b/kernel/events/core.c index acdd8b5..9335bce 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3199,6 +3199,7 @@ static void __perf_event_read(void *info) struct perf_event *sub, *event = data->event; struct perf_event_context *ctx = event->ctx; struct perf_cpu_context *cpuctx = __get_cpu_context(ctx); + struct pmu *pmu = event->pmu; /* * If this is a task context, we need to check whether it is @@ -3217,18 +3218,31 @@ static void __perf_event_read(void *info) } update_event_times(event); - if (event->state == PERF_EVENT_STATE_ACTIVE) - event->pmu->read(event); + if (event->state != PERF_EVENT_STATE_ACTIVE) + goto unlock; - if (!data->group) + if (!data->group) { + pmu->read(event); + data->ret = 0; goto unlock; + } + + pmu->start_txn(pmu, PERF_PMU_TXN_READ); + + pmu->read(event); list_for_each_entry(sub, &event->sibling_list, group_entry) { update_event_times(sub); - if (sub->state == PERF_EVENT_STATE_ACTIVE) + if (sub->state == PERF_EVENT_STATE_ACTIVE) { + /* + * Use sibling's PMU rather than @event's since + * sibling could be on different (eg: software) PMU. + */ sub->pmu->read(sub); + } } - data->ret = 0; + + data->ret = pmu->commit_txn(pmu); unlock: raw_spin_unlock(&ctx->lock); -- 1.7.9.5