From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
To: <linux-cxl@vger.kernel.org>
Cc: <peterz@infradead.org>, <mingo@redhat.com>, <acme@kernel.org>,
<mark.rutland@arm.com>, <will@kernel.org>,
<dan.j.williams@intel.com>, <bwidawsk@kernel.org>,
<ira.weiny@intel.com>, <vishal.l.verma@intel.com>,
<alison.schofield@intel.com>, <linuxarm@huawei.com>,
<linux-perf-users@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: [PATCH 4/4] docs: perf: Minimal introduction the the CXL PMU device and driver.
Date: Fri, 3 Mar 2023 17:50:22 +0000 [thread overview]
Message-ID: <20230303175022.10806-5-Jonathan.Cameron@huawei.com> (raw)
In-Reply-To: <20230303175022.10806-1-Jonathan.Cameron@huawei.com>
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 <Jonathan.Cameron@huawei.com>
--
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<id> on the CXL bus.
+
+ /sys/bus/cxl/device/cpmu<id>
+
+The associated PMU is registered as
+
+ /sys/bus/event_sources/devices/cpmu<id>
+
+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
next prev parent reply other threads:[~2023-03-03 17:52 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-03 17:50 [PATCH 0/4] CXL 3.0 Performance Monitoring Unit support Jonathan Cameron
2023-03-03 17:50 ` [PATCH 1/4] cxl: Add function to count regblocks of a given type Jonathan Cameron
2023-03-07 2:28 ` Davidlohr Bueso
2023-03-03 17:50 ` [PATCH 2/4] cxl/pci: Find and register CXL PMU devices Jonathan Cameron
2023-03-03 18:25 ` Dave Jiang
2023-03-04 2:46 ` kernel test robot
2023-03-06 11:12 ` Jonathan Cameron
2023-03-04 8:22 ` kernel test robot
2023-03-04 8:22 ` kernel test robot
2023-03-07 2:36 ` Davidlohr Bueso
2023-03-21 14:48 ` Jonathan Cameron
2023-03-03 17:50 ` [PATCH 3/4] cxl: CXL Performance Monitoring Unit driver Jonathan Cameron
2023-03-03 21:56 ` Liang, Kan
2023-03-06 14:41 ` Jonathan Cameron
2023-03-06 18:10 ` Liang, Kan
2023-03-07 9:19 ` Jonathan Cameron
2023-03-07 16:21 ` Liang, Kan
2023-03-21 17:46 ` Jonathan Cameron
2023-03-03 17:50 ` Jonathan Cameron [this message]
2023-03-03 18:34 ` [PATCH 4/4] docs: perf: Minimal introduction the the CXL PMU device and driver Dave Jiang
2023-03-06 10:27 ` Jonathan Cameron
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