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Message-ID: <CAP-5=fUWm7efu3xdUBbiifs_KNU1igwAxbXmum=V38SjHQHtXg@mail.gmail.com>
Date: Tue, 21 Nov 2023 08:09:37 -0800
From: Ian Rogers <irogers@...gle.com>
To: Mark Rutland <mark.rutland@....com>
Cc: Marc Zyngier <maz@...nel.org>, Hector Martin <marcan@...can.st>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
James Clark <james.clark@....com>,
linux-perf-users@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>,
Asahi Linux <asahi@...ts.linux.dev>
Subject: Re: [REGRESSION] Perf (userspace) broken on big.LITTLE systems since v6.5
On Tue, Nov 21, 2023 at 8:03 AM Mark Rutland <mark.rutland@....com> wrote:
>
> On Tue, Nov 21, 2023 at 07:46:57AM -0800, Ian Rogers wrote:
> > On Tue, Nov 21, 2023 at 7:40 AM Mark Rutland <mark.rutland@....com> wrote:
> > >
> > > On Tue, Nov 21, 2023 at 03:24:25PM +0000, Marc Zyngier wrote:
> > > > On Tue, 21 Nov 2023 13:40:31 +0000,
> > > > Marc Zyngier <maz@...nel.org> wrote:
> > > > >
> > > > > [Adding key people on Cc]
> > > > >
> > > > > On Tue, 21 Nov 2023 12:08:48 +0000,
> > > > > Hector Martin <marcan@...can.st> wrote:
> > > > > >
> > > > > > Perf broke on all Apple ARM64 systems (tested almost everything), and
> > > > > > according to maz also on Juno (so, probably all big.LITTLE) since v6.5.
> > > > >
> > > > > I can confirm that at least on 6.7-rc2, perf is pretty busted on any
> > > > > asymmetric ARM platform. It isn't clear what criteria is used to pick
> > > > > the PMU, but nothing works anymore.
> > > > >
> > > > > The saving grace in my case is that Debian still ships a 6.1 perftool
> > > > > package, but that's obviously not going to last.
> > > > >
> > > > > I'm happy to test potential fixes.
> > > >
> > > > At Mark's request, I've dumped a couple of perf (as of -rc2) runs with
> > > > -vvv. And it is quite entertaining (this is taskset to an 'icestorm'
> > > > CPU):
> > >
> > > IIUC the tool is doing the wrong thing here and overriding explicit
> > > ${pmu}/${event}/ events with PERF_TYPE_HARDWARE events rather than events using
> > > that ${pmu}'s type and event namespace.
> > >
> > > Regardless of the *new* ABI that allows PERF_TYPE_HARDWARE events to be
> > > targetted to a specific PMU, it's semantically wrong to rewrite events like
> > > this since ${pmu}/${event}/ is not necessarily equivalent to a similarly-named
> > > PERF_COUNT_HW_${EVENT}.
> >
> > If you name a PMU and an event then the event should only be opened on
> > that PMU, 100% agree. There's a bunch of output, but when the legacy
> > cycles event is opened it appears to be because it was explicitly
> > requested.
>
> I think you've missed that the named PMU events are being erreously transformed
> into PERF_TYPE_HARDWARE events. Look at the -vvv output, e.g.
>
> Opening: apple_firestorm_pmu/cycles/
> ------------------------------------------------------------
> perf_event_attr:
> type 0 (PERF_TYPE_HARDWARE)
> size 136
> config 0 (PERF_COUNT_HW_CPU_CYCLES)
> sample_type IDENTIFIER
> read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
> disabled 1
> inherit 1
> enable_on_exec 1
> exclude_guest 1
> ------------------------------------------------------------
> sys_perf_event_open: pid 1045843 cpu -1 group_fd -1 flags 0x8 = 4
>
> ... which should not be PERF_TYPE_HARDWARE && PERF_COUNT_HW_CPU_CYCLES.
>
> Marc said that he bisected the issue down to commit:
>
> 5ea8f2ccffb23983 ("perf parse-events: Support hardware events as terms")
>
> ... so it looks like something is going wrong when the events are being parsed,
> e.g. losing the HW PMU information?
Ok, I think I'm getting confused by other things. This looks like the issue.
I think it may be working as intended, but not how you intended :-) If
a core PMU is listed and then a legacy event, the legacy event should
be opened on the core PMU as a legacy event with the extended type
set. This is to allow things like legacy cache events to be opened on
a specified PMU. Legacy event names match with a higher priority than
those in sysfs or json as they are hard coded. Presumably the
expectation was that by advertising a cycles event, presumably in
sysfs, then this is what would be matched.
Thanks,
Ian
> Thanks,
> Mark.
>
> >
> >
> > Thanks,
> > Ian
> >
> > > Mark.
> > >
> > > > <quote>
> > > > maz@...ley-girl:~/hot-poop/arm-platforms/tools/perf$ sudo taskset -c 0 ./perf stat -vvv -e apple_icestorm_pmu/cycles/ -e
> > > > apple_firestorm_pmu/cycles/ -e cycles ls
> > > > Using CPUID 0x00000000612f0280
> > > > Attempt to add: apple_icestorm_pmu/cycles=0/
> > > > ..after resolving event: apple_icestorm_pmu/cycles=0/
> > > > Opening: unknown-hardware:HG
> > > > ------------------------------------------------------------
> > > > perf_event_attr:
> > > > type 0 (PERF_TYPE_HARDWARE)
> > > > config 0xb00000000
> > > > disabled 1
> > > > ------------------------------------------------------------
> > > > sys_perf_event_open: pid 0 cpu -1 group_fd -1 flags 0x8
> > > > sys_perf_event_open failed, error -95
> > > > Attempt to add: apple_firestorm_pmu/cycles=0/
> > > > ..after resolving event: apple_firestorm_pmu/cycles=0/
> > > > Control descriptor is not initialized
> > > > Opening: apple_icestorm_pmu/cycles/
> > > > ------------------------------------------------------------
> > > > perf_event_attr:
> > > > type 0 (PERF_TYPE_HARDWARE)
> > > > size 136
> > > > config 0 (PERF_COUNT_HW_CPU_CYCLES)
> > > > sample_type IDENTIFIER
> > > > read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
> > > > disabled 1
> > > > inherit 1
> > > > enable_on_exec 1
> > > > exclude_guest 1
> > > > ------------------------------------------------------------
> > > > sys_perf_event_open: pid 1045843 cpu -1 group_fd -1 flags 0x8 = 3
> > > > Opening: apple_firestorm_pmu/cycles/
> > > > ------------------------------------------------------------
> > > > perf_event_attr:
> > > > type 0 (PERF_TYPE_HARDWARE)
> > > > size 136
> > > > config 0 (PERF_COUNT_HW_CPU_CYCLES)
> > > > sample_type IDENTIFIER
> > > > read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
> > > > disabled 1
> > > > inherit 1
> > > > enable_on_exec 1
> > > > exclude_guest 1
> > > > ------------------------------------------------------------
> > > > sys_perf_event_open: pid 1045843 cpu -1 group_fd -1 flags 0x8 = 4
> > > > Opening: cycles
> > > > ------------------------------------------------------------
> > > > perf_event_attr:
> > > > type 0 (PERF_TYPE_HARDWARE)
> > > > size 136
> > > > config 0 (PERF_COUNT_HW_CPU_CYCLES)
> > > > sample_type IDENTIFIER
> > > > read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
> > > > disabled 1
> > > > inherit 1
> > > > enable_on_exec 1
> > > > exclude_guest 1
> > > > ------------------------------------------------------------
> > > > sys_perf_event_open: pid 1045843 cpu -1 group_fd -1 flags 0x8 = 5
> > > > arch builtin-diff.o builtin-mem.o common-cmds.h perf-completion.sh
> > > > bench builtin-evlist.c builtin-probe.c CREDITS perf.h
> > > > Build builtin-evlist.o builtin-probe.o design.txt perf-in.o
> > > > builtin-annotate.c builtin-ftrace.c builtin-record.c dlfilters perf-iostat
> > > > builtin-annotate.o builtin-ftrace.o builtin-record.o Documentation perf-iostat.sh
> > > > builtin-bench.c builtin.h builtin-report.c FEATURE-DUMP perf.o
> > > > builtin-bench.o builtin-help.c builtin-report.o include perf-read-vdso.c
> > > > builtin-buildid-cache.c builtin-help.o builtin-sched.c jvmti perf-sys.h
> > > > builtin-buildid-cache.o builtin-inject.c builtin-script.c libapi PERF-VERSION-FILE
> > > > builtin-buildid-list.c builtin-inject.o builtin-script.o libperf perf-with-kcore
> > > > builtin-buildid-list.o builtin-kallsyms.c builtin-stat.c libsubcmd pmu-events
> > > > builtin-c2c.c builtin-kallsyms.o builtin-stat.o libsymbol python
> > > > builtin-c2c.o builtin-kmem.c builtin-timechart.c Makefile python_ext_build
> > > > builtin-config.c builtin-kvm.c builtin-top.c Makefile.config scripts
> > > > builtin-config.o builtin-kvm.o builtin-top.o Makefile.perf tests
> > > > builtin-daemon.c builtin-kwork.c builtin-trace.c MANIFEST trace
> > > > builtin-daemon.o builtin-list.c builtin-version.c perf ui
> > > > builtin-data.c builtin-list.o builtin-version.o perf-archive util
> > > > builtin-data.o builtin-lock.c check-headers.sh perf-archive.sh
> > > > builtin-diff.c builtin-mem.c command-list.txt perf.c
> > > > apple_icestorm_pmu/cycles/: -1: 0 873709 0
> > > > apple_firestorm_pmu/cycles/: -1: 0 873709 0
> > > > cycles: -1: 0 873709 0
> > > > apple_icestorm_pmu/cycles/: 0 873709 0
> > > > apple_firestorm_pmu/cycles/: 0 873709 0
> > > > cycles: 0 873709 0
> > > >
> > > > Performance counter stats for 'ls':
> > > >
> > > > <not counted> apple_icestorm_pmu/cycles/ (0.00%)
> > > > <not counted> apple_firestorm_pmu/cycles/ (0.00%)
> > > > <not counted> cycles (0.00%)
> > > >
> > > > 0.000002250 seconds time elapsed
> > > >
> > > > 0.000000000 seconds user
> > > > 0.000000000 seconds sys
> > > > </quote>
> > > >
> > > > If I run the same thing on another CPU cluster (firestorm), I get
> > > > this:
> > > >
> > > > <quote>
> > > > maz@...ley-girl:~/hot-poop/arm-platforms/tools/perf$ sudo taskset -c 2 ./perf stat -vvv -e apple_icestorm_pmu/cycles/ -e
> > > > apple_firestorm_pmu/cycles/ -e cycles ls
> > > > Using CPUID 0x00000000612f0280
> > > > Attempt to add: apple_icestorm_pmu/cycles=0/
> > > > ..after resolving event: apple_icestorm_pmu/cycles=0/
> > > > Opening: unknown-hardware:HG
> > > > ------------------------------------------------------------
> > > > perf_event_attr:
> > > > type 0 (PERF_TYPE_HARDWARE)
> > > > config 0xb00000000
> > > > disabled 1
> > > > ------------------------------------------------------------
> > > > sys_perf_event_open: pid 0 cpu -1 group_fd -1 flags 0x8
> > > > sys_perf_event_open failed, error -95
> > > > Attempt to add: apple_firestorm_pmu/cycles=0/
> > > > ..after resolving event: apple_firestorm_pmu/cycles=0/
> > > > Control descriptor is not initialized
> > > > Opening: apple_icestorm_pmu/cycles/
> > > > ------------------------------------------------------------
> > > > perf_event_attr:
> > > > type 0 (PERF_TYPE_HARDWARE)
> > > > size 136
> > > > config 0 (PERF_COUNT_HW_CPU_CYCLES)
> > > > sample_type IDENTIFIER
> > > > read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
> > > > disabled 1
> > > > inherit 1
> > > > enable_on_exec 1
> > > > exclude_guest 1
> > > > ------------------------------------------------------------
> > > > sys_perf_event_open: pid 1045925 cpu -1 group_fd -1 flags 0x8 = 3
> > > > Opening: apple_firestorm_pmu/cycles/
> > > > ------------------------------------------------------------
> > > > perf_event_attr:
> > > > type 0 (PERF_TYPE_HARDWARE)
> > > > size 136
> > > > config 0 (PERF_COUNT_HW_CPU_CYCLES)
> > > > sample_type IDENTIFIER
> > > > read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
> > > > disabled 1
> > > > inherit 1
> > > > enable_on_exec 1
> > > > exclude_guest 1
> > > > ------------------------------------------------------------
> > > > sys_perf_event_open: pid 1045925 cpu -1 group_fd -1 flags 0x8 = 4
> > > > Opening: cycles
> > > > ------------------------------------------------------------
> > > > perf_event_attr:
> > > > type 0 (PERF_TYPE_HARDWARE)
> > > > size 136
> > > > config 0 (PERF_COUNT_HW_CPU_CYCLES)
> > > > sample_type IDENTIFIER
> > > > read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
> > > > disabled 1
> > > > inherit 1
> > > > enable_on_exec 1
> > > > exclude_guest 1
> > > > ------------------------------------------------------------
> > > > sys_perf_event_open: pid 1045925 cpu -1 group_fd -1 flags 0x8 = 5
> > > > arch builtin-diff.o builtin-mem.o common-cmds.h perf-completion.sh
> > > > bench builtin-evlist.c builtin-probe.c CREDITS perf.h
> > > > Build builtin-evlist.o builtin-probe.o design.txt perf-in.o
> > > > builtin-annotate.c builtin-ftrace.c builtin-record.c dlfilters perf-iostat
> > > > builtin-annotate.o builtin-ftrace.o builtin-record.o Documentation perf-iostat.sh
> > > > builtin-bench.c builtin.h builtin-report.c FEATURE-DUMP perf.o
> > > > builtin-bench.o builtin-help.c builtin-report.o include perf-read-vdso.c
> > > > builtin-buildid-cache.c builtin-help.o builtin-sched.c jvmti perf-sys.h
> > > > builtin-buildid-cache.o builtin-inject.c builtin-script.c libapi PERF-VERSION-FILE
> > > > builtin-buildid-list.c builtin-inject.o builtin-script.o libperf perf-with-kcore
> > > > builtin-buildid-list.o builtin-kallsyms.c builtin-stat.c libsubcmd pmu-events
> > > > builtin-c2c.c builtin-kallsyms.o builtin-stat.o libsymbol python
> > > > builtin-c2c.o builtin-kmem.c builtin-timechart.c Makefile python_ext_build
> > > > builtin-config.c builtin-kvm.c builtin-top.c Makefile.config scripts
> > > > builtin-config.o builtin-kvm.o builtin-top.o Makefile.perf tests
> > > > builtin-daemon.c builtin-kwork.c builtin-trace.c MANIFEST trace
> > > > builtin-daemon.o builtin-list.c builtin-version.c perf ui
> > > > builtin-data.c builtin-list.o builtin-version.o perf-archive util
> > > > builtin-data.o builtin-lock.c check-headers.sh perf-archive.sh
> > > > builtin-diff.c builtin-mem.c command-list.txt perf.c
> > > > apple_icestorm_pmu/cycles/: -1: 1035101 469125 469125
> > > > apple_firestorm_pmu/cycles/: -1: 1035035 469125 469125
> > > > cycles: -1: 1034653 469125 469125
> > > > apple_icestorm_pmu/cycles/: 1035101 469125 469125
> > > > apple_firestorm_pmu/cycles/: 1035035 469125 469125
> > > > cycles: 1034653 469125 469125
> > > >
> > > > Performance counter stats for 'ls':
> > > >
> > > > 1,035,101 apple_icestorm_pmu/cycles/
> > > > 1,035,035 apple_firestorm_pmu/cycles/
> > > > 1,034,653 cycles
> > > >
> > > > 0.000001333 seconds time elapsed
> > > >
> > > > 0.000000000 seconds user
> > > > 0.000000000 seconds sys
> > > > </quote>
> > > >
> > > > which doesn't make any sense either. I really don't understand what
> > > > this PERF_TYPE_HARDWARE does here (the *real* types are 10 and 11),
> > > > nor what this 'cycle=0' stuff is.
> > > >
> > > > /puzzled
> > > >
> > > > M.
> > > >
> > > > --
> > > > Without deviation from the norm, progress is not possible.
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