by Ian Rogers

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Subject: Re: [PATCH v4 00/44] Fix perf on Intel hybrid CPUs

On Sun, May 14, 2023 at 5:03 AM Liang, Kan <[email protected]> wrote:
>
>
>
> On 2023-05-12 2:33 p.m., Arnaldo Carvalho de Melo wrote:
> > Em Wed, May 03, 2023 at 04:56:36PM -0400, Liang, Kan escreveu:
> >>
> >>
> >> On 2023-05-02 6:38 p.m., Ian Rogers wrote:
> >>> TL;DR: hybrid doesn't crash, json metrics work on hybrid on both PMUs
> >>> or individually, event parsing doesn't always scan all PMUs, more and
> >>> new tests that also run without hybrid, less code.
> >>>
> >>> The first 4 patches are aimed at Linux 6.4 to address issues raised,
> >>> in particular by Kan, on the existing perf stat behavior with json
> >>> metrics. They avoid duplicated events by removing groups. They don't
> >>> hide events and metrics to make event multiplexing obvious. They avoid
> >>> terminating perf when paranoia is higher due to certain events that
> >>> always fail. They avoid rearranging events by PMUs when the events
> >>> aren't in a group.
> >>>
> >>> The next 5 patches avoid grouping events for metrics where they could
> >>> never succeed and were previously posted as:
> >>> "perf vendor events intel: Add xxx metric constraints"
> >>> https://lore.kernel.org/all/[email protected]/
> >>> In general the generated json is coming from:
> >>> https://github.com/intel/perfmon/pull/73
> >>>
> >>> Next are some general and test improvements.
> >>>
> >>> Next event parsing is rewritten to not scan all PMUs for the benefit
> >>> of raw and legacy cache parsing, instead these are handled by the
> >>> lexer and a new term type. This ultimately removes the need for the
> >>> event parser for hybrid to be recursive as legacy cache can be just a
> >>> term. Tests are re-enabled for events with hyphens, so AMD's
> >>> branch-brs event is now parsable.
> >>>
> >>> The cputype option is made a generic pmu filter flag and is tested
> >>> even on non-hybrid systems.
> >>>
> >>> The final patches address specific json metric issues on hybrid, in
> >>> both the json metrics and the metric code.
> >>>
> >>> The patches add slightly more code than they remove, in areas like
> >>> better json metric constraints and tests, but in the core util code,
> >>> the removal of hybrid is a net reduction:
> >>> 22 files changed, 711 insertions(+), 1016 deletions(-)
> >>>
> >>> Sample output is contained in the v1 patch set:
> >>> https://lore.kernel.org/lkml/[email protected]/
> >>>
> >>> Tested on Tigerlake, Skylake and Alderlake CPUs.
> >>>
> >>> The v4 patch set:
> >>> - rebase, 1 of the Linux 6.4 recommended patches are merged leaving:
> >>> 1) perf metric: Change divide by zero and !support events behavior
> >>> 2) perf stat: Introduce skippable evsels
> >>> 3) perf metric: Json flag to not group events if gathering a metric group
> >>> 4) perf parse-events: Don't reorder ungrouped events by pmu
> >>> whose diffstat is:
> >>> 30 files changed, 326 insertions(+), 33 deletions(-)
> >>> but without the vendor event updates (the tend to be large as they
> >>> repeat something per architecture per metric) is just:
> >>> 10 files changed, 90 insertions(+), 32 deletions(-)
> >>
> >> I have tested the 4 patches on top of the perf-tools-next branch on both
> >> Cascade Lake and Raptor Lake. The result looks good to me.
> >>
> >> They address the permission error found in the default mode of perf stat
> >> on the Cascade Lake. Thanks Ian for the fix.
> >>
> >> Arnaldo, could you please consider to back port them for the 6.4?
> >
> > Yes, its in perf-tools now, will go to Linus next week.
>
> Thanks Arnaldo!
>
> >
> > What about the other patches? I saw some you provided your review, what
> > about the others, are you ok with them?
> >
>
> Yes, I'm OK with the patch set. It fixes many issues. Thanks Ian.
> (My tests mainly focus on the area in which the patch set may touch. I
> did the tests on various platforms, ADL (hybrid), Cascade Lake, SPR.)
>
> Tested-by: Kan Liang <[email protected]>
>
> But there are still some issues. I don't think they are introduced by
> this patch set. We may fix them later separately.
>
> - Segmentation fault with perf stat --topdown on ADL (hybrid) and
> Cascade Lake.
> It looks like a legacy issue, may not be introduced by this patch set.
> Here is the backtrace. It looks like there is a NULL metric_group.
>
> (gdb) backtrace
> #0 0x00007ffff73035d1 in __strstr_sse2_unaligned () from /lib64/libc.so.6
> #1 0x00000000004f9019 in metricgroup__topdown_max_level_callback
> (pm=<optimized out>, table=<optimized out>,
> data=0x7fffffff92f4) at util/metricgroup.c:1722
> #2 0x00000000005e8a31 in pmu_metrics_table_for_each_metric
> (table=0xcb74d0 <pmu_events_map+368>,
> fn=fn@entry=0x4f8ff0 <metricgroup__topdown_max_level_callback>,
> data=data@entry=0x7fffffff92f4)
> at pmu-events/pmu-events.c:61123
> #3 0x00000000004fbc3b in metricgroups__topdown_max_level () at
> util/metricgroup.c:1742
> #4 0x000000000042c135 in add_default_attributes () at builtin-stat.c:1845
> #5 cmd_stat (argc=0, argv=0x7fffffffe3e0) at builtin-stat.c:2446
> #6 0x00000000004b922b in run_builtin (p=p@entry=0xd5c530
> <commands+336>, argc=argc@entry=2,
> argv=argv@entry=0x7fffffffe3e0) at perf.c:323
> #7 0x000000000040e373 in handle_internal_command (argv=0x7fffffffe3e0,
> argc=2) at perf.c:377
> #8 run_argv (argv=<synthetic pointer>, argcp=<synthetic pointer>) at
> perf.c:421
> #9 main (argc=2, argv=0x7fffffffe3e0) at perf.c:537
> (gdb)

Thanks, there's a 1-liner for the segv:
https://lore.kernel.org/lkml/[email protected]/
Arnaldo, can we make sure this goes toward the next 6.4 release candidate?

Thanks,
Ian

> Also, the return type is unsigned int, but a bool is given.
>
> unsigned int metricgroups__topdown_max_level(void)
> {
> unsigned int max_level = 0;
> const struct pmu_metrics_table *table = pmu_metrics_table__find();
>
> if (!table)
> return false;
>
>
>
> - The perf metric and metricgroups fail on different platforms.
> Ian and I have discussed it. We agree to address it later separately.
>
> 102: perf all metricgroups test
> ADL (hybrid)
> 103: perf all metrics test
> ADL (hybrid), Cascade Lake, SPR
>
> - perf list: The [Kernel PMU event] is missed for all the hardware cache
> events.
> It impacts both hybrid and non-hybrid platforms.
> It's a user-visible change introduced by the patch set.
> I don't know if anyone cares whether it's a kernel event or a regular
> event. It doesn't bother me. So I'm OK with it.
>
> cpu:
> L1-dcache-loads OR cpu/L1-dcache-loads/
> L1-dcache-load-misses OR cpu/L1-dcache-load-misses/
> L1-dcache-stores OR cpu/L1-dcache-stores/
> L1-icache-load-misses OR cpu/L1-icache-load-misses/
> LLC-loads OR cpu/LLC-loads/
> LLC-load-misses OR cpu/LLC-load-misses/
> LLC-stores OR cpu/LLC-stores/
> LLC-store-misses OR cpu/LLC-store-misses/
> dTLB-loads OR cpu/dTLB-loads/
> dTLB-load-misses OR cpu/dTLB-load-misses/
> dTLB-stores OR cpu/dTLB-stores/
> dTLB-store-misses OR cpu/dTLB-store-misses/
> iTLB-load-misses OR cpu/iTLB-load-misses/
> branch-loads OR cpu/branch-loads/
> branch-load-misses OR cpu/branch-load-misses/
> node-loads OR cpu/node-loads/
> node-load-misses OR cpu/node-load-misses/
> branch-instructions OR cpu/branch-instructions/ [Kernel PMU event]
> branch-misses OR cpu/branch-misses/ [Kernel PMU event]
> bus-cycles OR cpu/bus-cycles/ [Kernel PMU event]
> cache-misses OR cpu/cache-misses/ [Kernel PMU event]
> cache-references OR cpu/cache-references/ [Kernel PMU event]
> cpu-cycles OR cpu/cpu-cycles/ [Kernel PMU event]
> instructions OR cpu/instructions/ [Kernel PMU event]
>
>
> - The --cputype only works for the metric in the default mode.
> I can still see the cpu_atom events with --cputype core
> It may be something we can improve later.
>
> # ./perf stat --cputype core sleep 2
>
> Performance counter stats for 'sleep 2':
>
> 0.52 msec task-clock # 0.000 CPUs
> utilized
> 1 context-switches # 1.939 K/sec
> 0 cpu-migrations # 0.000 /sec
> 69 page-faults # 133.770 K/sec
> 2,569,423 cpu_core/cycles/ # 4.981 G/sec
> <not counted> cpu_atom/cycles/
> (0.00%)
> 3,287,691 cpu_core/instructions/ # 6.374 G/sec
> <not counted> cpu_atom/instructions/
> (0.00%)
> 555,848 cpu_core/branches/ # 1.078 G/sec
> <not counted> cpu_atom/branches/
> (0.00%)
> 8,398 cpu_core/branch-misses/ # 16.281 M/sec
> <not counted> cpu_atom/branch-misses/
> (0.00%)
> 15,416,538 cpu_core/TOPDOWN.SLOTS/ # 36.1 %
> tma_backend_bound
> # 23.9 % tma_retiring
> # 5.6 %
> tma_bad_speculation
> # 34.4 %
> tma_frontend_bound
> 3,687,877 cpu_core/topdown-retiring/
> 846,398 cpu_core/topdown-bad-spec/
> 5,320,217 cpu_core/topdown-fe-bound/
> 5,562,045 cpu_core/topdown-be-bound/
> 14,149 cpu_core/INT_MISC.UOP_DROPPING/ # 27.431 M/sec
>
>
> Thanks,
> Kan

2023-05-16 18:27:34

by Arnaldo Carvalho de Melo

[permalink] [raw]

Subject: Re: [PATCH v4 00/44] Fix perf on Intel hybrid CPUs

Em Mon, May 15, 2023 at 03:49:45PM -0700, Ian Rogers escreveu:
> On Sun, May 14, 2023 at 5:03 AM Liang, Kan <[email protected]> wrote:
> > - Segmentation fault with perf stat --topdown on ADL (hybrid) and
> > Cascade Lake.
> > It looks like a legacy issue, may not be introduced by this patch set.
> > Here is the backtrace. It looks like there is a NULL metric_group.
> >
> > (gdb) backtrace
> > #0 0x00007ffff73035d1 in __strstr_sse2_unaligned () from /lib64/libc.so.6
> > #1 0x00000000004f9019 in metricgroup__topdown_max_level_callback
> > (pm=<optimized out>, table=<optimized out>,
> > data=0x7fffffff92f4) at util/metricgroup.c:1722
> > #2 0x00000000005e8a31 in pmu_metrics_table_for_each_metric
> > (table=0xcb74d0 <pmu_events_map+368>,
> > fn=fn@entry=0x4f8ff0 <metricgroup__topdown_max_level_callback>,
> > data=data@entry=0x7fffffff92f4)
> > at pmu-events/pmu-events.c:61123
> > #3 0x00000000004fbc3b in metricgroups__topdown_max_level () at
> > util/metricgroup.c:1742
> > #4 0x000000000042c135 in add_default_attributes () at builtin-stat.c:1845
> > #5 cmd_stat (argc=0, argv=0x7fffffffe3e0) at builtin-stat.c:2446
> > #6 0x00000000004b922b in run_builtin (p=p@entry=0xd5c530
> > <commands+336>, argc=argc@entry=2,
> > argv=argv@entry=0x7fffffffe3e0) at perf.c:323
> > #7 0x000000000040e373 in handle_internal_command (argv=0x7fffffffe3e0,
> > argc=2) at perf.c:377
> > #8 run_argv (argv=<synthetic pointer>, argcp=<synthetic pointer>) at
> > perf.c:421
> > #9 main (argc=2, argv=0x7fffffffe3e0) at perf.c:537
> > (gdb)
>
> Thanks, there's a 1-liner for the segv:
> https://lore.kernel.org/lkml/[email protected]/
> Arnaldo, can we make sure this goes toward the next 6.4 release candidate?

Sure.

- Arnaldo