1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 ====================================== 3 ======================================
4 CXL Performance Monitoring Unit (CPMU) 4 CXL Performance Monitoring Unit (CPMU)
5 ====================================== 5 ======================================
6 6
7 The CXL rev 3.0 specification provides a defin 7 The CXL rev 3.0 specification provides a definition of CXL Performance
8 Monitoring Unit in section 13.2: Performance M 8 Monitoring Unit in section 13.2: Performance Monitoring.
9 9
10 CXL components (e.g. Root Port, Switch Upstrea 10 CXL components (e.g. Root Port, Switch Upstream Port, End Point) may have
11 any number of CPMU instances. CPMU capabilitie 11 any number of CPMU instances. CPMU capabilities are fully discoverable from
12 the devices. The specification provides event 12 the devices. The specification provides event definitions for all CXL protocol
13 message types and a set of additional events f 13 message types and a set of additional events for things commonly counted on
14 CXL devices (e.g. DRAM events). 14 CXL devices (e.g. DRAM events).
15 15
16 CPMU driver 16 CPMU driver
17 =========== 17 ===========
18 18
19 The CPMU driver registers a perf PMU with the 19 The CPMU driver registers a perf PMU with the name pmu_mem<X>.<Y> on the CXL bus
20 representing the Yth CPMU for memX. 20 representing the Yth CPMU for memX.
21 21
22 /sys/bus/cxl/device/pmu_mem<X>.<Y> 22 /sys/bus/cxl/device/pmu_mem<X>.<Y>
23 23
24 The associated PMU is registered as 24 The associated PMU is registered as
25 25
26 /sys/bus/event_sources/devices/cxl_pmu_mem< 26 /sys/bus/event_sources/devices/cxl_pmu_mem<X>.<Y>
27 27
28 In common with other CXL bus devices, the id h 28 In common with other CXL bus devices, the id has no specific meaning and the
29 relationship to specific CXL device should be 29 relationship to specific CXL device should be established via the device parent
30 of the device on the CXL bus. 30 of the device on the CXL bus.
31 31
32 PMU driver provides description of available e 32 PMU driver provides description of available events and filter options in sysfs.
33 33
34 The "format" directory describes all formats o 34 The "format" directory describes all formats of the config (event vendor id,
35 group id and mask) config1 (threshold, filter 35 group id and mask) config1 (threshold, filter enables) and config2 (filter
36 parameters) fields of the perf_event_attr stru 36 parameters) fields of the perf_event_attr structure. The "events" directory
37 describes all documented events show in perf l 37 describes all documented events show in perf list.
38 38
39 The events shown in perf list are the most fin 39 The events shown in perf list are the most fine grained events with a single
40 bit of the event mask set. More general events 40 bit of the event mask set. More general events may be enable by setting
41 multiple mask bits in config. For example, all 41 multiple mask bits in config. For example, all Device to Host Read Requests
42 may be captured on a single counter by setting 42 may be captured on a single counter by setting the bits for all of
43 43
44 * d2h_req_rdcurr 44 * d2h_req_rdcurr
45 * d2h_req_rdown 45 * d2h_req_rdown
46 * d2h_req_rdshared 46 * d2h_req_rdshared
47 * d2h_req_rdany 47 * d2h_req_rdany
48 * d2h_req_rdownnodata 48 * d2h_req_rdownnodata
49 49
50 Example of usage:: 50 Example of usage::
51 51
52 $#perf list 52 $#perf list
53 cxl_pmu_mem0.0/clock_ticks/ 53 cxl_pmu_mem0.0/clock_ticks/ [Kernel PMU event]
54 cxl_pmu_mem0.0/d2h_req_rdshared/ 54 cxl_pmu_mem0.0/d2h_req_rdshared/ [Kernel PMU event]
55 cxl_pmu_mem0.0/h2d_req_snpcur/ 55 cxl_pmu_mem0.0/h2d_req_snpcur/ [Kernel PMU event]
56 cxl_pmu_mem0.0/h2d_req_snpdata/ 56 cxl_pmu_mem0.0/h2d_req_snpdata/ [Kernel PMU event]
57 cxl_pmu_mem0.0/h2d_req_snpinv/ 57 cxl_pmu_mem0.0/h2d_req_snpinv/ [Kernel PMU event]
58 -------------------------------------------- 58 -----------------------------------------------------------
59 59
60 $# perf stat -a -e cxl_pmu_mem0.0/clock_tick 60 $# perf stat -a -e cxl_pmu_mem0.0/clock_ticks/ -e cxl_pmu_mem0.0/d2h_req_rdshared/
61 61
62 Vendor specific events may also be available a 62 Vendor specific events may also be available and if so can be used via
63 63
64 $# perf stat -a -e cxl_pmu_mem0.0/vid=VID,gi 64 $# perf stat -a -e cxl_pmu_mem0.0/vid=VID,gid=GID,mask=MASK/
65 65
66 The driver does not support sampling so "perf 66 The driver does not support sampling so "perf record" is unsupported.
67 It only supports system-wide counting so attac 67 It only supports system-wide counting so attaching to a task is
68 unsupported. 68 unsupported.
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