| Message ID | 20220824103617.21781-5-Jonathan.Cameron@huawei.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | CXL 3.0 Performance Monitoring Unit support | expand |
On 8/24/2022 3:36 AM, 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. > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > -- > 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..6ffc057591fb > --- /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<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. "all the documented events shown in perf list." DJ > + > +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 9c9ece88ce53..f12cfe76e1f0 100644 > --- a/Documentation/admin-guide/perf/index.rst > +++ b/Documentation/admin-guide/perf/index.rst > @@ -18,3 +18,4 @@ Performance monitor support > xgene-pmu > arm_dsu_pmu > thunderx2-pmu > + cxl
diff --git a/Documentation/admin-guide/perf/cxl.rst b/Documentation/admin-guide/perf/cxl.rst new file mode 100644 index 000000000000..6ffc057591fb --- /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<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/ + +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 9c9ece88ce53..f12cfe76e1f0 100644 --- a/Documentation/admin-guide/perf/index.rst +++ b/Documentation/admin-guide/perf/index.rst @@ -18,3 +18,4 @@ Performance monitor support xgene-pmu arm_dsu_pmu thunderx2-pmu + cxl
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> -- 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(+)