From patchwork Tue Oct 18 12:13:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 13010460 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 379EDC433FE for ; Tue, 18 Oct 2022 12:15:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229526AbiJRMPv (ORCPT ); Tue, 18 Oct 2022 08:15:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52422 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229572AbiJRMPu (ORCPT ); Tue, 18 Oct 2022 08:15:50 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72278A285E; Tue, 18 Oct 2022 05:15:47 -0700 (PDT) Received: from fraeml704-chm.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4MsCRS6tHMz67PDP; Tue, 18 Oct 2022 20:12:36 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (7.191.163.240) by fraeml704-chm.china.huawei.com (10.206.15.53) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2375.31; Tue, 18 Oct 2022 14:15:45 +0200 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 15.1.2375.31; Tue, 18 Oct 2022 13:15:44 +0100 From: Jonathan Cameron To: , Dave Jiang CC: , Dan Williams , "Alison Schofield" , Vishal Verma , Ira Weiny , Ben Widawsky , , Will Deacon , Mark Rutland , Davidlohr Bueso Subject: [RFC PATCH v3 5/5] docs: perf: Minimal introduction the the CXL PMU device and driver. Date: Tue, 18 Oct 2022 13:13:18 +0100 Message-ID: <20221018121318.22385-6-Jonathan.Cameron@huawei.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20221018121318.22385-1-Jonathan.Cameron@huawei.com> References: <20221018121318.22385-1-Jonathan.Cameron@huawei.com> MIME-Version: 1.0 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-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. Signed-off-by: Jonathan Cameron --- 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 | 60 ++++++++++++++++++++++++ Documentation/admin-guide/perf/index.rst | 1 + 2 files changed, 61 insertions(+) diff --git a/Documentation/admin-guide/perf/cxl.rst b/Documentation/admin-guide/perf/cxl.rst new file mode 100644 index 000000000000..5105ae484e08 --- /dev/null +++ b/Documentation/admin-guide/perf/cxl.rst @@ -0,0 +1,60 @@ +====================================== +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 the 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/ + +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 793e1970bc05..db7828f1f4ef 100644 --- a/Documentation/admin-guide/perf/index.rst +++ b/Documentation/admin-guide/perf/index.rst @@ -19,3 +19,4 @@ Performance monitor support arm_dsu_pmu thunderx2-pmu alibaba_pmu + cxl