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 C8483C64EC4 for ; Fri, 3 Mar 2023 17:52:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231477AbjCCRw6 (ORCPT ); Fri, 3 Mar 2023 12:52:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231315AbjCCRwy (ORCPT ); Fri, 3 Mar 2023 12:52:54 -0500 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8DF805C101; Fri, 3 Mar 2023 09:52:28 -0800 (PST) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4PSwR30nKVz67JXs; Sat, 4 Mar 2023 01:47:27 +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 15.1.2507.21; Fri, 3 Mar 2023 17:52:26 +0000 From: Jonathan Cameron To: CC: , , , , , , , , , , , , Subject: [PATCH 4/4] docs: perf: Minimal introduction the the CXL PMU device and driver. Date: Fri, 3 Mar 2023 17:50:22 +0000 Message-ID: <20230303175022.10806-5-Jonathan.Cameron@huawei.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20230303175022.10806-1-Jonathan.Cameron@huawei.com> References: <20230303175022.10806-1-Jonathan.Cameron@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.122.247.231] X-ClientProxiedBy: lhrpeml100005.china.huawei.com (7.191.160.25) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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. Signed-off-by: Jonathan Cameron -- v1: - Add docs for how to use a Vendor Defined Counter. RFC: - I'll post separately about this shortly, but it seems very odd to me that there is no way to assign a parent to an event_sources device. As a result we get the messy approach of playing match the name to figure out what the CPMU instance is connected to. --- Documentation/admin-guide/perf/cxl.rst | 65 ++++++++++++++++++++++++ Documentation/admin-guide/perf/index.rst | 1 + 2 files changed, 66 insertions(+) diff --git a/Documentation/admin-guide/perf/cxl.rst b/Documentation/admin-guide/perf/cxl.rst new file mode 100644 index 000000000000..46235dff4b21 --- /dev/null +++ b/Documentation/admin-guide/perf/cxl.rst @@ -0,0 +1,65 @@ +.. 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 register a perf PMU with the name cpmu on the CXL bus. + + /sys/bus/cxl/device/cpmu + +The associated PMU is registered as + + /sys/bus/event_sources/devices/cpmu + +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 + cpmu0/clock_ticks/ [Kernel PMU event] + cpmu0/d2h_req_itomwr/ [Kernel PMU event] + cpmu0/d2h_req_rdany/ [Kernel PMU event] + cpmu0/d2h_req_rdcurr/ [Kernel PMU event] + ----------------------------------------------------------- + + $# perf stat -e cpmu0/clock_ticks/ -e cpmu0/d2h_req_itowrm/ + +Vendor specific events may also be available and if so can be used via + + $# perf stat -e cpmu0/vid=VID,gid=GID,mask=MASK/ + +The driver does not support sampling. So "perf record" and attaching to +a task are 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 -- 2.37.2