From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e37.co.us.ibm.com (e37.co.us.ibm.com [32.97.110.158]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 949021A001E for ; Wed, 15 Jul 2015 13:03:10 +1000 (AEST) Received: from /spool/local by e37.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 14 Jul 2015 21:03:08 -0600 Received: from b03cxnp08025.gho.boulder.ibm.com (b03cxnp08025.gho.boulder.ibm.com [9.17.130.17]) by d03dlp01.boulder.ibm.com (Postfix) with ESMTP id 7BA191FF0043 for ; Tue, 14 Jul 2015 20:54:16 -0600 (MDT) Received: from d03av05.boulder.ibm.com (d03av05.boulder.ibm.com [9.17.195.85]) by b03cxnp08025.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t6F32JeD52887670 for ; Tue, 14 Jul 2015 20:02:19 -0700 Received: from d03av05.boulder.ibm.com (localhost [127.0.0.1]) by d03av05.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t6F335Gu026942 for ; Tue, 14 Jul 2015 21:03:06 -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 v3 7/8] perf: Define PMU_TXN_READ interface Date: Tue, 14 Jul 2015 20:01:54 -0700 Message-Id: <1436929315-28520-8-git-send-email-sukadev@linux.vnet.ibm.com> In-Reply-To: <1436929315-28520-1-git-send-email-sukadev@linux.vnet.ibm.com> References: <1436929315-28520-1-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. 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 --- include/linux/perf_event.h | 1 + kernel/events/core.c | 35 +++++++++++++++++++++++++++++++++-- 2 files changed, 34 insertions(+), 2 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 44bf05f..da307ad 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 a83d45c..2ea06c4 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3763,6 +3763,33 @@ static void orphans_remove_work(struct work_struct *work) put_ctx(ctx); } +/* + * Use the transaction interface to read the group of events in @leader. + * PMUs like the 24x7 counters in Power, can use this to queue the events + * in the ->read() operation and perform the actual read in ->commit_txn. + * + * Other PMUs can ignore the ->start_txn and ->commit_txn and read each + * PMU directly in the ->read() operation. + */ +static int perf_event_read_group(struct perf_event *leader) +{ + int ret; + struct perf_event *sub; + struct pmu *pmu; + + pmu = leader->pmu; + + pmu->start_txn(pmu, PERF_PMU_TXN_READ); + + perf_event_read(leader); + list_for_each_entry(sub, &leader->sibling_list, group_entry) + perf_event_read(sub); + + ret = pmu->commit_txn(pmu); + + return ret; +} + u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running) { u64 total = 0; @@ -3792,7 +3819,11 @@ static int perf_read_group(struct perf_event *event, lockdep_assert_held(&ctx->mutex); - count = perf_event_read_value(leader, &enabled, &running); + ret = perf_event_read_group(leader); + if (ret) + return ret; + + count = perf_event_compute(leader, &enabled, &running); values[n++] = 1 + leader->nr_siblings; if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) @@ -3813,7 +3844,7 @@ static int perf_read_group(struct perf_event *event, list_for_each_entry(sub, &leader->sibling_list, group_entry) { n = 0; - values[n++] = perf_event_read_value(sub, &enabled, &running); + values[n++] = perf_event_compute(sub, &enabled, &running); if (read_format & PERF_FORMAT_ID) values[n++] = primary_event_id(sub); -- 1.7.9.5