From patchwork Thu Apr 13 14:26:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 13210353 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8BCE1C77B61 for ; Thu, 13 Apr 2023 14:28:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229999AbjDMO25 (ORCPT ); Thu, 13 Apr 2023 10:28:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229638AbjDMO24 (ORCPT ); Thu, 13 Apr 2023 10:28:56 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C21444B6; Thu, 13 Apr 2023 07:28:51 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Py23p5MXpz67ngg; Thu, 13 Apr 2023 22:27:50 +0800 (CST) Received: from SecurePC-101-06.china.huawei.com (10.122.247.231) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Thu, 13 Apr 2023 15:28:49 +0100 From: Jonathan Cameron To: Liang Kan , , , , CC: , , , , , , Davidlohr Bueso , Dave Jiang Subject: [PATCH v6 5/5] docs: perf: Minimal introduction the the CXL PMU device and driver Date: Thu, 13 Apr 2023 15:26:17 +0100 Message-ID: <20230413142617.15995-6-Jonathan.Cameron@huawei.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20230413142617.15995-1-Jonathan.Cameron@huawei.com> References: <20230413142617.15995-1-Jonathan.Cameron@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.122.247.231] X-ClientProxiedBy: lhrpeml500001.china.huawei.com (7.191.163.213) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org Very basic introduction to the device and the current driver support provided. I expect to expand on this in future versions of this patch set. Reviewed-by: Dave Jiang Reviewed-by: Kan Liang Signed-off-by: Jonathan Cameron --- v6: - Tags applied. v5: - Correct final statemnt about sampling support. (Kan) - Update CXL PMU MAINTAINERS entry to include this documentation - Update device naming to cxl_pmu_memX.Y etc --- Documentation/admin-guide/perf/cxl.rst | 68 ++++++++++++++++++++++++ Documentation/admin-guide/perf/index.rst | 1 + MAINTAINERS | 1 + 3 files changed, 70 insertions(+) diff --git a/Documentation/admin-guide/perf/cxl.rst b/Documentation/admin-guide/perf/cxl.rst new file mode 100644 index 000000000000..2a1c684603bb --- /dev/null +++ b/Documentation/admin-guide/perf/cxl.rst @@ -0,0 +1,68 @@ +.. SPDX-License-Identifier: GPL-2.0 + +====================================== +CXL Performance Monitoring Unit (CPMU) +====================================== + +The CXL rev 3.0 specification provides a definition of CXL Performance +Monitoring Unit in section 13.2: Performance Monitoring. + +CXL components (e.g. Root Port, Switch Upstream Port, End Point) may have +any number of CPMU instances. CPMU capabilities are fully discoverable from +the devices. The specification provides event definitions for all CXL protocol +message types and a set of additional events for things commonly counted on +CXL devices (e.g. DRAM events). + +CPMU driver +=========== + +The CPMU driver registers a perf PMU with the name pmu_mem. on the CXL bus +representing the Yth CPMU for memX. + + /sys/bus/cxl/device/pmu_mem. + +The associated PMU is registered as + + /sys/bus/event_sources/devices/cxl_pmu_mem. + +In common with other CXL bus devices, the id has no specific meaning and the +relationship to specific CXL device should be established via the device parent +of the device on the CXL bus. + +PMU driver provides description of available events and filter options in sysfs. + +The "format" directory describes all formats of the config (event vendor id, +group id and mask) config1 (threshold, filter enables) and config2 (filter +parameters) fields of the perf_event_attr structure. The "events" directory +describes all documented events show in perf list. + +The events shown in perf list are the most fine grained events with a single +bit of the event mask set. More general events may be enable by setting +multiple mask bits in config. For example, all Device to Host Read Requests +may be captured on a single counter by setting the bits for all of + +* d2h_req_rdcurr +* d2h_req_rdown +* d2h_req_rdshared +* d2h_req_rdany +* d2h_req_rdownnodata + +Example of usage:: + + $#perf list + cxl_pmu_mem0.0/clock_ticks/ [Kernel PMU event] + cxl_pmu_mem0.0/d2h_req_rdshared/ [Kernel PMU event] + cxl_pmu_mem0.0/h2d_req_snpcur/ [Kernel PMU event] + cxl_pmu_mem0.0/h2d_req_snpdata/ [Kernel PMU event] + cxl_pmu_mem0.0/h2d_req_snpinv/ [Kernel PMU event] + ----------------------------------------------------------- + + $# perf stat -e cxl_pmu_mem0.0/clock_ticks/ -e cxl_pmu_mem0.0/d2h_req_rdshared/ + +Vendor specific events may also be available and if so can be used via + + $# perf stat -e cxl_pmu_mem0.0/vid=VID,gid=GID,mask=MASK/ + +The driver does not support sampling so "perf record" is unsupported. +It only supports system-wide counting so attaching to a task is +unsupported. diff --git a/Documentation/admin-guide/perf/index.rst b/Documentation/admin-guide/perf/index.rst index 9de64a40adab..f60be04e4e33 100644 --- a/Documentation/admin-guide/perf/index.rst +++ b/Documentation/admin-guide/perf/index.rst @@ -21,3 +21,4 @@ Performance monitor support alibaba_pmu nvidia-pmu meson-ddr-pmu + cxl diff --git a/MAINTAINERS b/MAINTAINERS index 51234eb7858e..29a108afa065 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -5178,6 +5178,7 @@ COMPUTE EXPRESS LINK PMU (CPMU) M: Jonathan Cameron L: linux-cxl@vger.kernel.org S: Maintained +F: Documentation/admin-guide/perf/cxl.rst F: drivers/perf/cxl_pmu.c CONEXANT ACCESSRUNNER USB DRIVER