From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e8.ny.us.ibm.com (e8.ny.us.ibm.com [32.97.182.138]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id D3BCA1A0ACE for ; Wed, 8 Apr 2015 10:35:14 +1000 (AEST) Received: from /spool/local by e8.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 7 Apr 2015 20:35:12 -0400 Received: from b01cxnp22033.gho.pok.ibm.com (b01cxnp22033.gho.pok.ibm.com [9.57.198.23]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id 7A8466E804A for ; Tue, 7 Apr 2015 20:26:59 -0400 (EDT) Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t380Z9h330081130 for ; Wed, 8 Apr 2015 00:35:09 GMT Received: from d01av03.pok.ibm.com (localhost [127.0.0.1]) by d01av03.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t380Z9Pq016678 for ; Tue, 7 Apr 2015 20:35:09 -0400 From: Sukadev Bhattiprolu To: Paul Mackerras , Arnaldo Carvalho de Melo , mingo@redhat.com, peterz@infradead.org, Michael Ellerman Subject: [PATCH v2 4/5] perf: Define PMU_TXN_READ interface Date: Tue, 7 Apr 2015 17:34:58 -0700 Message-Id: <1428453299-19121-5-git-send-email-sukadev@linux.vnet.ibm.com> In-Reply-To: <1428453299-19121-1-git-send-email-sukadev@linux.vnet.ibm.com> References: <1428453299-19121-1-git-send-email-sukadev@linux.vnet.ibm.com> Cc: linuxppc-dev@lists.ozlabs.org, dev@codyps.com, linux-kernel@vger.kernel.org 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 will queue the counters to be read in ->read() and read them all at once in ->commit_txn(). PMUs that don't implement PERF_PMU_TXN_READ will continue to read one counter at a time and ignore the ->start_txn() and ->commit_txn(). Thanks to input from Peter Zijlstra. Signed-off-by: Sukadev Bhattiprolu --- include/linux/perf_event.h | 1 + kernel/events/core.c | 33 +++++++++++++++++++++++++++++++-- 2 files changed, 32 insertions(+), 2 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index e684c6b..3e46a07 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -244,6 +244,7 @@ struct pmu { * Optional. */ #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 */ void (*start_txn) (struct pmu *pmu, int flags); /* * If ->start_txn() disabled the ->add() schedulability test diff --git a/kernel/events/core.c b/kernel/events/core.c index 1ac99d1..a001582 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3644,6 +3644,33 @@ 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_txn(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, PERF_PMU_TXN_READ); + + return ret; +} + u64 perf_event_compute_values(struct perf_event *event, u64 *enabled, u64 *running) { @@ -3685,7 +3712,10 @@ static int perf_event_read_group(struct perf_event *event, lockdep_assert_held(&ctx->mutex); - perf_event_read(leader); + ret = perf_event_read_txn(leader); + if (ret) + return ret; + count = perf_event_compute_values(leader, &enabled, &running); values[n++] = 1 + leader->nr_siblings; @@ -3707,7 +3737,6 @@ static int perf_event_read_group(struct perf_event *event, list_for_each_entry(sub, &leader->sibling_list, group_entry) { n = 0; - perf_event_read(sub); values[n++] = perf_event_compute_values(sub, &enabled, &running); if (read_format & PERF_FORMAT_ID) values[n++] = primary_event_id(sub); -- 1.7.9.5