On 01/06/17 16:11, Arnaldo Carvalho de Melo wrote: > Em Fri, May 26, 2017 at 02:31:40PM +0200, Jiri Olsa escreveu: >> The switch tracking test keeps failing on P4 cpu, >> when NMI watchdog is enabled. >> >> The reason is that P4 pmu uses substitute event for cycles >> when it's already taken (in our case by NMI watchdog), but >> this event does not give even results like cycles, and we >> could end up with no samples at all for our short >> measuring period.
Did you consider increasing the measuring period? >> >> Fixing this by using "instructions:u" event instead, >> which seems to be stable enough. > > The original author of this test entry is Adrian, so would be nice for > him to take a look and give his Ack, Adrian? > > - Arnaldo > >> Cc: Michael Petlan <[email protected]> >> Link: http://lkml.kernel.org/n/[email protected] >> Signed-off-by: Jiri Olsa <[email protected]> >> --- >> tools/perf/tests/switch-tracking.c | 27 +++++++++++++++++++++++++-- >> 1 file changed, 25 insertions(+), 2 deletions(-) >> >> diff --git a/tools/perf/tests/switch-tracking.c >> b/tools/perf/tests/switch-tracking.c >> index 65474fd80da7..e519819ea2e5 100644 >> --- a/tools/perf/tests/switch-tracking.c >> +++ b/tools/perf/tests/switch-tracking.c >> @@ -10,6 +10,7 @@ >> #include "thread_map.h" >> #include "cpumap.h" >> #include "tests.h" >> +#include "header.h" >> >> static int spin_sleep(void) >> { >> @@ -298,6 +299,27 @@ static int process_events(struct perf_evlist *evlist, >> return ret; >> } >> >> +static const char *get_hw_counter(void) >> +{ >> + const char *counter = "cycles:u"; >> + char *cpuid; >> + >> + cpuid = get_cpuid_str(); >> + >> + /* >> + * P4 pmu uses substitute event for cycles if it's already >> + * taken, but it does not give even results like cycles, >> + * and we could end up with no samples at all for our short >> + * measuring period. Using "instructions:u" event instead, >> + * which seems to be stable enough. >> + */ >> + if (!strcmp("GenuineIntel-15-4", cpuid)) Why just model 4? Isn't all family 15 P4? >> + counter = "instructions:u"; >> + >> + pr_debug("using '%s' HW counter"); tests/switch-tracking.c: In function ‘get_hw_counter’: tests/switch-tracking.c:319:2: error: format ‘%s’ expects a matching ‘char *’ argument [-Werror=format=] >> + return counter; >> +} >> + >> /** >> * test__switch_tracking - test using sched_switch and tracking events. >> * >> @@ -308,6 +330,7 @@ static int process_events(struct perf_evlist *evlist, >> */ >> int test__switch_tracking(int subtest __maybe_unused) >> { >> + const char *hw_counter = get_hw_counter(); >> const char *sched_switch = "sched:sched_switch"; >> struct switch_tracking switch_tracking = { .tids = NULL, }; >> struct record_opts opts = { >> @@ -357,9 +380,9 @@ int test__switch_tracking(int subtest __maybe_unused) >> cpu_clocks_evsel = perf_evlist__last(evlist); >> >> /* Second event */ >> - err = parse_events(evlist, "cycles:u", NULL); >> + err = parse_events(evlist, hw_counter, NULL); >> if (err) { >> - pr_debug("Failed to parse event cycles:u\n"); >> + pr_debug("Failed to parse event %s\n", hw_counter); >> goto out_err; >> } >> >> -- >> 2.9.4 >
