diff options
author | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2023-05-26 12:58:24 +0300 |
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committer | Dan Williams <dan.j.williams@intel.com> | 2023-06-26 03:47:09 +0300 |
commit | c2b34d442226b69e519eb0ba61939a74d91712d4 (patch) | |
tree | 14b56a31ba9551e377c1726321566fd9a665c288 | |
parent | 5d7107c72796df3be2ba574f1cf6eca75c60d5ef (diff) | |
download | linux-c2b34d442226b69e519eb0ba61939a74d91712d4.tar.xz |
docs: perf: Minimal introduction the the CXL PMU device and driver
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 <dave.jiang@intel.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20230526095824.16336-6-Jonathan.Cameron@huawei.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
-rw-r--r-- | Documentation/admin-guide/perf/cxl.rst | 68 | ||||
-rw-r--r-- | Documentation/admin-guide/perf/index.rst | 1 | ||||
-rw-r--r-- | MAINTAINERS | 1 |
3 files changed, 70 insertions, 0 deletions
diff --git a/Documentation/admin-guide/perf/cxl.rst b/Documentation/admin-guide/perf/cxl.rst new file mode 100644 index 000000000000..9233ea0d0b10 --- /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<X>.<Y> on the CXL bus +representing the Yth CPMU for memX. + + /sys/bus/cxl/device/pmu_mem<X>.<Y> + +The associated PMU is registered as + + /sys/bus/event_sources/devices/cxl_pmu_mem<X>.<Y> + +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 -a -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 -a -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 e0ede1ed1361..aefb5ef084be 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -5197,6 +5197,7 @@ COMPUTE EXPRESS LINK PMU (CPMU) M: Jonathan Cameron <jonathan.cameron@huawei.com> 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 |