Messages in this thread |  | | Subject | Re: [PATCH] perf list: Add s390 support for detailed/verbose pmu event description | From | Thomas-Mich Richter <> | Date | Mon, 9 Apr 2018 15:03:32 +0200 |
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On 04/09/2018 01:37 PM, Mark Rutland wrote: > Hi, > > On Mon, Apr 09, 2018 at 01:00:15PM +0200, Thomas Richter wrote: >> From: Thomas Richter <tmricht@linux.vnet.ibm.com> >> >> Perf list with flags -d and -v print a description (-d) or >> a very verbose explanation (-v) of CPU specific counter events. >> These descriptions are provided with the json files in >> directory pmu-events/arch/s390/*.json. >> >> Display of these descriptions on s390 requires the >> corresponding json files. >> >> On s390 this does not work because function is_pmu_core() >> does not detect the s390 directory name where the >> CPU specific events are listed. On x86 it is >> /sys/bus/event_source/devices/cpu >> whereas on s390 it is >> /sys/bus/event_source/devices/cpum_cf >> /sys/bus/event_source/devices/cpum_sf >> >> Fix this by adding s390 directory name testing to >> function is_pmu_core(). This is the same approach as taken for >> arm platform. > > I don't think this is quite right. > > On arm, we specifically look for PMU directories which have a > file called CPUs. e.g. > > /sys/bus/event_source/devices/arm_pmuv3/cpus > > ... where "arm_pmuv3" is the PMU name. > >> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c >> index 1111d5bf15ca..8675ddf558c6 100644 >> --- a/tools/perf/util/pmu.c >> +++ b/tools/perf/util/pmu.c >> @@ -562,6 +562,12 @@ static int is_pmu_core(const char *name) >> if (stat(path, &st) == 0) >> return 1; >> >> + /* Look for cpu sysfs (specific to s390) */ >> + scnprintf(path, PATH_MAX, "%s/bus/event_source/devices/%s", >> + sysfs, name); >> + if (stat(path, &st) == 0) >> + return 1; > > IIUC here we return true if the PMU has a sysfs directory, but all PMUs > (including uncore PMUs) should have such a directory, so this will make > is_pmu_core() always return true. > > Can you match the "cpum_" prefix specifically, instead? > > Thanks, > Mark. >
I am sorry, I don't follow you. When I look at the code function sequence
perf_pmu__scan() +---> pmu_read_sysfs() This functions scans directory /sys/bus/event_source/devices/ and calls for each entry in this directory. For s390 these entries exist: cpum_sf cpum_cf tracepoint and software +---> perf_pmu__find(); +---> pmu_lookup() +---> pmu_format() Looks for file /sys/bus/event_source/devices/cpum_cf/format/event and parses its contents. This returns 0 on s390. +---> pmu_type() Looks for file /sys/bus/event_source/devices/cpum_cf/type and and parses its contents. This returns 0 on s390. +---> pmu_aliases() Looks for directory /sys/bus/event_source/devices/cpum_cf/events and reads out every entry name which is treated as a event name and added to the list of PMU-Aliases together with the file contents. For example /sys/bus/event_source/devices/cpum_cf/events/SF_CYCLES_BASIC with the file contents event=0xb0000. This is the raw event number. +----> pmu_aliases_parse() + perf_pmu__new_alias() Check and add alias name to a list. +---> pmu_cpumask() This tests for files /sys/bus/event_source/devices/cpum_cf/cpus or /sys/bus/event_source/devices/cpum_cf/cpumask which do not exist on s390. +---> pmu_add_cpu_aliases() adds the list of aliases such as cpum_sf/SF_CYCLES_BASIC/ to the global list of aliases. But ths happens only when +---> is_pmu_core() function returns true. And for s390 it needs to test for /sys/bus/event_source/devices/cpum_sf/ and /sys/bus/event_source/devices/cpum_cf/ directories. These directories are used to read the alias names in function pmu_aliases() above. Maybe I misunderstand this whole scheme, but with this patch the perf list commands works...
-- Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany -- Vorsitzende des Aufsichtsrats: Martina Koederitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294
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