Re: [REGRESSION] 'perf mem record' on a Intel hybrid system broken

["Liang, Kan" <kan.liang@linux.intel.com>]

On 2024-12-04 2:24 p.m., Namhyung Kim wrote:
> Hi Arnaldo,
> 
> On Wed, Dec 04, 2024 at 02:45:48PM -0300, Arnaldo Carvalho de Melo wrote:
>> Hi Namhyung,
>>
>> root@number:/tmp# perf mem record -a sleep 1s
>> Error:
>> The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cpu_core/mem-loads,ldlat=30/).
>> "dmesg | grep -i perf" may provide additional information.
>>
>> root@number:/tmp# dmesg | tail
>> [18865.729882] ixgbe 0000:05:00.0 enp5s0: NIC Link is Up 10 Gbps, Flow Control: RX/TX
>> [18865.848172] mlx5_core 0000:01:00.0 enp1s0f0np0: Link down
>> [18866.057990] mlx5_core 0000:01:00.1 enp1s0f1np1: Link down
>> [19066.396215] input: JBL RACE TWS (AVRCP) as /devices/virtual/input/input27
>> [19078.378477] usb 2-3: current rate 16000 is different from the runtime rate 48000
>> [21158.375680] usb 2-3: current rate 16000 is different from the runtime rate 48000
>> [31386.186675] input: JBL RACE TWS (AVRCP) as /devices/virtual/input/input28
>> [31409.098352] usb 2-3: current rate 16000 is different from the runtime rate 48000
>> [36409.737615] sysrq: Emergency Sync
>> [36409.742619] Emergency Sync complete
>> root@number:/tmp#
>>
>> 	That I bisected down to:
>>
>> ⬢ [acme@toolbox perf-tools-next]$ git bisect good 
>> af954f76eea56453713ae657f6812d4063f9bc57 is the first bad commit
>> commit af954f76eea56453713ae657f6812d4063f9bc57
>> Author: Namhyung Kim <namhyung@kernel.org>
>> Date:   Tue Oct 15 23:23:57 2024 -0700
>>
>>     perf tools: Check fallback error and order
>>     
>>     The perf_event_open might fail due to various reasons, so blindly
>>     reducing precise_ip level might not be the best way to deal with it.
>>     
>>     It seems the kernel return -EOPNOTSUPP when PMU doesn't support the
>>     given precise level.  Let's try again with the correct error code.
>>     
>>     This caused a problem on AMD, as it stops on precise_ip of 2 for IBS but
>>     user events with exclude_kernel=1 cannot make progress.  Let's add the
>>     evsel__handle_error_quirks() to this case specially.  I plan to work on
>>     the kernel side to improve this situation but it'd still need some
>>     special handling for IBS.
>>     
>>     Reviewed-by: James Clark <james.clark@linaro.org>
>>     Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
>>     Acked-by: Kan Liang <kan.liang@linux.intel.com>
>>     Cc: James Clark <james.clark@arm.com>
>>     Cc: Atish Patra <atishp@atishpatra.org>
>>     Cc: Mingwei Zhang <mizhang@google.com>
>>     Cc: Kajol Jain <kjain@linux.ibm.com>
>>     Cc: Thomas Richter <tmricht@linux.ibm.com>
>>     Cc: Palmer Dabbelt <palmer@rivosinc.com>
>>     Link: https://lore.kernel.org/r/20241016062359.264929-8-namhyung@kernel.org
>>     Signed-off-by: Namhyung Kim <namhyung@kernel.org>
>>
>> If I revert that patch:
>>
>> ⬢ [acme@toolbox perf-tools-next]$ git log --oneline -5
>> 9a9f2d6da1ea5ef5 (HEAD -> perf-tools-next) Revert "perf tools: Check fallback error and order"
>> d12d4cfc5033cd8c perf script python: Improve physical mem type resolution
>> 3f79d822e331022f perf disasm: Return a proper error when not determining the file type
>> 1a5b914261f0ebee tools features: Don't check for libunwind devel files by default
>> 40384c840ea1944d (tag: v6.13-rc1, perf-tools/perf-tools) Linux 6.13-rc1
>> ⬢ [acme@toolbox perf-tools-next]$
>>
>> And rebuild, it works again:
>>
>> root@number:/tmp# perf mem record -a sleep 1s
>> [ perf record: Woken up 1 times to write data ]
>> [ perf record: Captured and wrote 13.014 MB perf.data (10316 samples) ]
>> root@number:/tmp# perf evlist
>> cpu_atom/mem-loads,ldlat=30/P
>> cpu_atom/mem-stores/P
>> cpu_core/mem-loads-aux/
>> cpu_core/mem-loads,ldlat=30/
>> cpu_core/mem-stores/P
>> dummy:u
>> # Tip: use 'perf evlist -g' to show group information
>> root@number:/tmp# perf evlist -v
>> cpu_atom/mem-loads,ldlat=30/P: type: 10 (cpu_atom), size: 136, config: 0x5d0 (mem-loads), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|ADDR|CPU|PERIOD|IDENTIFIER|DATA_SRC|WEIGHT_STRUCT, read_format: ID|LOST, disabled: 1, freq: 1, precise_ip: 3, sample_id_all: 1, { bp_addr, config1 }: 0x1f
>> cpu_atom/mem-stores/P: type: 10 (cpu_atom), size: 136, config: 0x6d0 (mem-stores), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|ADDR|CPU|PERIOD|IDENTIFIER|DATA_SRC|WEIGHT_STRUCT, read_format: ID|LOST, disabled: 1, freq: 1, precise_ip: 3, sample_id_all: 1
>> cpu_core/mem-loads-aux/: type: 4 (cpu_core), size: 136, config: 0x8203 (mem-loads-aux), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|ADDR|CPU|PERIOD|IDENTIFIER|DATA_SRC|WEIGHT_STRUCT, read_format: ID|LOST, disabled: 1, freq: 1, precise_ip: 3, sample_id_all: 1
>> cpu_core/mem-loads,ldlat=30/: type: 4 (cpu_core), size: 136, config: 0x1cd (mem-loads), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|ADDR|CPU|PERIOD|IDENTIFIER|DATA_SRC|WEIGHT_STRUCT, read_format: ID|LOST, freq: 1, precise_ip: 2, sample_id_all: 1, { bp_addr, config1 }: 0x1f
>> cpu_core/mem-stores/P: type: 4 (cpu_core), size: 136, config: 0x2cd (mem-stores), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|ADDR|CPU|PERIOD|IDENTIFIER|DATA_SRC|WEIGHT_STRUCT, read_format: ID|LOST, disabled: 1, freq: 1, precise_ip: 3, sample_id_all: 1
>> dummy:u: type: 1 (software), size: 136, config: 0x9 (PERF_COUNT_SW_DUMMY), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|ADDR|CPU|IDENTIFIER|DATA_SRC|WEIGHT_STRUCT, read_format: ID|LOST, exclude_kernel: 1, exclude_hv: 1, mmap: 1, comm: 1, task: 1, mmap_data: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
>> # Tip: use 'perf evlist -g' to show group information
>> root@number:/tmp# perf evlist -g
>> cpu_atom/mem-loads,ldlat=30/P
>> cpu_atom/mem-stores/P
>> {cpu_core/mem-loads-aux/,cpu_core/mem-loads,ldlat=30/}
>> cpu_core/mem-stores/P
>> dummy:u
>> root@number:/tmp#
>>
>> Now trying to investigate this,
> 
> I think I got a related report from the kernel test robot but it was a
> Sapphire Rapids machine.  I don't have a Intel hybrid machine in hand.
> I'll try to take a look at it on Sapphire Rapids.

The default precise_ip level for perf mem is always 3.

For the latest intel platforms, it implies PDist, which is only
available on GP 0.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/events/intel/core.c#n4412

However, the mem-load PEBS event is available on all GP counters but GP
0. :(
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/events/intel/ds.c#n1176

So the precise_ip-- is required.

The failure of scheduling returns -EINVAL.

But Namhyung's patch assumes that the kernel return -EOPNOTSUPP when PMU
doesn't support the given precise level.
(Sorry, I didn't notice the case early.)

Is it possible to reduce the precise_ip for the -EINVAL as well?

Thanks,
Kan