Messages in this thread | | | Date | Tue, 4 Apr 2023 17:55:37 +0100 | From | Jonathan Cameron <> | Subject | Re: [PATCH v4 5/5] docs: perf: Minimal introduction the the CXL PMU device and driver |
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On Mon, 3 Apr 2023 13:45:52 -0400 "Liang, Kan" <kan.liang@linux.intel.com> wrote:
> On 2023-03-30 12:45 p.m., Jonathan Cameron wrote: > > 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> > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > > > -- > > v4: No change > > --- > > 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. > > The PMU only supports system-wide counting. That's the reason it doesn't > support per-task profiling. Not because of missing sampling.
Ah. I've managed to fuse two different conditions. I'll break them apart for v5.
Thanks,
Jonathan
> > Thanks, > Kan > > 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 >
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