On Wed, Dec 4, 2024 at 9:47 PM Namhyung Kim <namhy...@kernel.org> wrote:
>
> Hi Ian,
>
> On Wed, Dec 04, 2024 at 06:23:05PM -0800, Ian Rogers wrote:
> > The refactoring of tool PMU events to have a PMU then adding the expr
> > literals to the tool PMU made it so that the literal system_tsc_freq
> > was only supported on x86. Update the test expectations to match -
> > namely the parsing is x86 specific and only yields a non-zero value on
> > Intel.
> >
> > Fixes: 609aa2667f67 ("perf tool_pmu: Switch to standard pmu functions and
> > json descriptions")
> > Reported-by: Athira Rajeev <atraj...@linux.vnet.ibm.com>
> > Closes:
> > https://lore.kernel.org/linux-perf-users/20241022140156.98854-1-atraj...@linux.vnet.ibm.com/
> > Co-developed-by: Athira Rajeev <atraj...@linux.vnet.ibm.com>
> > Signed-off-by: Ian Rogers <irog...@google.com>
>
> It failed on my VM.
>
> root@arm64-vm:~/build# ./perf test -v 7
> --- start ---
> test child forked, pid 2096
> Using CPUID 0x00000000000f0510
> division by zero
> syntax error
> Unrecognized literal '#system_tsc_freq'FAILED tests/expr.c:253
> #system_tsc_freq == 0
> ---- end(-1) ----
> 7: Simple expression parser :
> FAILED!
I'll need to check this. The test is looking for parsing failures, so
it's confusing to me expr__parse is returning 0. I was testing on x86
but disabling the literal in the tool PMU.
> > ---
> > tools/perf/tests/expr.c | 19 ++++++++++++-------
> > 1 file changed, 12 insertions(+), 7 deletions(-)
> >
> > diff --git a/tools/perf/tests/expr.c b/tools/perf/tests/expr.c
> > index 41ff1affdfcd..726cf8d4da28 100644
> > --- a/tools/perf/tests/expr.c
> > +++ b/tools/perf/tests/expr.c
> > @@ -75,14 +75,12 @@ static int test__expr(struct test_suite *t
> > __maybe_unused, int subtest __maybe_u
> > double val, num_cpus_online, num_cpus, num_cores, num_dies,
> > num_packages;
> > int ret;
> > struct expr_parse_ctx *ctx;
> > - bool is_intel = false;
> > char strcmp_cpuid_buf[256];
> > struct perf_cpu cpu = {-1};
> > char *cpuid = get_cpuid_allow_env_override(cpu);
> > char *escaped_cpuid1, *escaped_cpuid2;
> >
> > TEST_ASSERT_VAL("get_cpuid", cpuid);
> > - is_intel = strstr(cpuid, "Intel") != NULL;
> >
> > TEST_ASSERT_EQUAL("ids_union", test_ids_union(), 0);
> >
> > @@ -245,12 +243,19 @@ static int test__expr(struct test_suite *t
> > __maybe_unused, int subtest __maybe_u
> > if (num_dies) // Some platforms do not have CPU die support, for
> > example s390
> > TEST_ASSERT_VAL("#num_dies >= #num_packages", num_dies >=
> > num_packages);
> >
> > - TEST_ASSERT_VAL("#system_tsc_freq", expr__parse(&val, ctx,
> > "#system_tsc_freq") == 0);
> > - if (is_intel)
> > - TEST_ASSERT_VAL("#system_tsc_freq > 0", val > 0);
> > - else
> > - TEST_ASSERT_VAL("#system_tsc_freq == 0", fpclassify(val) ==
> > FP_ZERO);
> >
> > + if (expr__parse(&val, ctx, "#system_tsc_freq") == 0) {
> > + bool is_intel = strstr(cpuid, "Intel") != NULL;
> > +
> > + if (is_intel)
> > + TEST_ASSERT_VAL("#system_tsc_freq > 0", val > 0);
>
> Also Sasha reported that some (Intel?) guest machine doesn't have TSC
> frequency.
I think, unfortunately, this is working as intended. Intel metrics use
#system_tsc_freq in metrics for most models:
```
$ grep -ril system_tsc_freq tools/perf/pmu-events/arch/x86/
tools/perf/pmu-events/arch/x86/emeraldrapids/emr-metrics.json
tools/perf/pmu-events/arch/x86/broadwellx/bdx-metrics.json
tools/perf/pmu-events/arch/x86/haswellx/hsx-metrics.json
tools/perf/pmu-events/arch/x86/grandridge/grr-metrics.json
tools/perf/pmu-events/arch/x86/icelakex/icx-metrics.json
tools/perf/pmu-events/arch/x86/sierraforest/srf-metrics.json
tools/perf/pmu-events/arch/x86/skylakex/skx-metrics.json
tools/perf/pmu-events/arch/x86/cascadelakex/clx-metrics.json
tools/perf/pmu-events/arch/x86/sapphirerapids/spr-metrics.json
```
The code to generate the TSC frequency uses the CPUID leaf
information, but this can be disabled by the host operating system for
guest operating systems. The fallback logic using `/proc/cpuinfo` is
intended for older models and it appears the more recent formatting
won't be parse-able by perf. The host has also likely disabled the
information if the CPUID leaf is hidden. So the test is correctly
failing because metrics using #system_tsc_freq would be broken inside
the guest OS. Kan was involved in the conversation when the literal
was added and this was the best we could do.
Thanks,
Ian
> > + else
> > + TEST_ASSERT_VAL("#system_tsc_freq == 0",
> > fpclassify(val) == FP_ZERO);
> > + } else {
> > +#if defined(__i386__) || defined(__x86_64__)
> > + TEST_ASSERT_VAL("#system_tsc_freq unsupported", 0);
> > +#endif
> > + }
> > /*
> > * Source count returns the number of events aggregating in a leader
> > * event including the leader. Check parsing yields an id.
> > --
> > 2.47.0.338.g60cca15819-goog
> >
