From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id AB0227D910 for ; Mon, 20 May 2019 15:27:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388317AbfETP1w (ORCPT ); Mon, 20 May 2019 11:27:52 -0400 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:46474 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1733303AbfETP1w (ORCPT ); Mon, 20 May 2019 11:27:52 -0400 Received: from pps.filterd (m0046661.ppops.net [127.0.0.1]) by mx08-00178001.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x4KFLJQj031963; Mon, 20 May 2019 17:27:19 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=st.com; h=from : to : cc : subject : date : message-id : references : in-reply-to : content-type : content-transfer-encoding : mime-version; s=STMicroelectronics; bh=LkTdd7E2MxZuZ4AhmICRbNTuZ1ixfkA53WYKdrN9npk=; b=Dqs5gJtazuH92by9IDSNRvPO/j/HtIJpg+wTeVFrAQF9ZLMLW+zgdbWwbrMlFlXA/hb6 zGAmgEHwWpyBSIah5OWEllDOVwNU0xfeHhSniDYFEGn+e3KPKGyzAvNPi2FJjwhZJMQQ Fc+7gCUpyJbs+LQGhRN2UxuL6pqKL/yzTzol0v0eXwaKHACq9grjNFyZNFlUArkgjY+1 4VNMmDGMvjFicm25D6Som/4o+6S/GlVMcPjNOzl/ehB6CuLAdNZ4+NNkuQjMmFd9Gt7/ fOQna5khAGhlly1NkTOr6pK6awl1myTR6wl5vD12cz6b8k3leDcAPRi5qiSovflVPi+Y uw== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx08-00178001.pphosted.com with ESMTP id 2sj8xg450b-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Mon, 20 May 2019 17:27:19 +0200 Received: from zeta.dmz-eu.st.com (zeta.dmz-eu.st.com [164.129.230.9]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id C51AC3A; Mon, 20 May 2019 15:27:16 +0000 (GMT) Received: from Webmail-eu.st.com (sfhdag5node3.st.com [10.75.127.15]) by zeta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 955D32BAD; Mon, 20 May 2019 15:27:16 +0000 (GMT) Received: from SFHDAG5NODE1.st.com (10.75.127.13) by SFHDAG5NODE3.st.com (10.75.127.15) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 20 May 2019 17:27:16 +0200 Received: from SFHDAG5NODE1.st.com ([fe80::cc53:528c:36c8:95f6]) by SFHDAG5NODE1.st.com ([fe80::cc53:528c:36c8:95f6%20]) with mapi id 15.00.1347.000; Mon, 20 May 2019 17:27:16 +0200 From: Gerald BAEZA To: "will.deacon@arm.com" , "mark.rutland@arm.com" , "robh+dt@kernel.org" , "mcoquelin.stm32@gmail.com" , Alexandre TORGUE , "corbet@lwn.net" , "linux@armlinux.org.uk" , "olof@lixom.net" , "horms+renesas@verge.net.au" , "arnd@arndb.de" CC: "linux-arm-kernel@lists.infradead.org" , "devicetree@vger.kernel.org" , "linux-stm32@st-md-mailman.stormreply.com" , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" , Gerald BAEZA Subject: [PATCH v2 1/5] Documentation: perf: stm32: ddrperfm support Thread-Topic: [PATCH v2 1/5] Documentation: perf: stm32: ddrperfm support Thread-Index: AQHVDyCBNdrf91E160uuVjvaW40lug== Date: Mon, 20 May 2019 15:27:15 +0000 Message-ID: <1558366019-24214-2-git-send-email-gerald.baeza@st.com> References: <1558366019-24214-1-git-send-email-gerald.baeza@st.com> In-Reply-To: <1558366019-24214-1-git-send-email-gerald.baeza@st.com> Accept-Language: fr-FR, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.75.127.45] Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-20_07:,, signatures=0 Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org The DDRPERFM is the DDR Performance Monitor embedded in STM32MP1 SOC. This documentation introduces the DDRPERFM, the stm32-ddr-pmu driver supporting it and how to use it with the perf tool. Signed-off-by: Gerald Baeza --- Documentation/perf/stm32-ddr-pmu.txt | 41 ++++++++++++++++++++++++++++++++= ++++ 1 file changed, 41 insertions(+) create mode 100644 Documentation/perf/stm32-ddr-pmu.txt diff --git a/Documentation/perf/stm32-ddr-pmu.txt b/Documentation/perf/stm3= 2-ddr-pmu.txt new file mode 100644 index 0000000..d5b35b3 --- /dev/null +++ b/Documentation/perf/stm32-ddr-pmu.txt @@ -0,0 +1,41 @@ +STM32 DDR Performance Monitor (DDRPERFM) +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +The DDRPERFM is the DDR Performance Monitor embedded in STM32MP1 SOC. +See STM32MP157 reference manual RM0436 to get a description of this periph= eral. + + +The five following counters are supported by stm32-ddr-pmu driver: + cnt0: read operations counters (read_cnt) + cnt1: write operations counters (write_cnt) + cnt2: active state counters (activate_cnt) + cnt3: idle state counters (idle_cnt) + tcnt: time count, present for all sets (time_cnt) + +The stm32-ddr-pmu driver relies on the perf PMU framework to expose the +counters via sysfs: + $ ls /sys/bus/event_source/devices/ddrperfm/events + activate_cnt idle_cnt read_cnt time_cnt write_cnt + + +The perf PMU framework is usually invoked via the 'perf stat' tool. + +The DDRPERFM is a system monitor that cannot isolate the traffic coming fr= om a +given thread or CPU, that is why stm32-ddr-pmu driver rejects any 'perf st= at' +call that does not request a system-wide collection: the '-a, --all-cpus' +option is mandatory! + +Example: + $ perf stat -e ddrperfm/read_cnt/,ddrperfm/time_cnt/ -a sleep 20 + Performance counter stats for 'system wide': + + 342541560 ddrperfm/read_cnt/ + 10660011400 ddrperfm/time_cnt/ + + 20.021068551 seconds time elapsed + + +The driver also exposes a 'bandwidth' attribute that can be used to displa= y +the read/write/total bandwidth achieved during the last 'perf stat' execut= ion. + $ cat /sys/bus/event_source/devices/ddrperfm/bandwidth + Read =3D 403, Write =3D 239, Read & Write =3D 642 (MB/s) --=20 2.7.4