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Message-ID: <31449397-cbee-5c51-859d-887b6455c886@huawei.com>
Date: Thu, 7 Sep 2023 10:40:48 +0800
From: Yang Jihong <yangjihong1@...wei.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
CC: <peterz@...radead.org>, <mingo@...hat.com>, <mark.rutland@....com>,
<alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
<namhyung@...nel.org>, <irogers@...gle.com>,
<adrian.hunter@...el.com>, <kan.liang@...ux.intel.com>,
<james.clark@....com>, <tmricht@...ux.ibm.com>,
<ak@...ux.intel.com>, <anshuman.khandual@....com>,
<linux-kernel@...r.kernel.org>, <linux-perf-users@...r.kernel.org>
Subject: Re: [PATCH v8 0/6] perf record: Track sideband events for all CPUs
when tracing selected CPUs
Hello,
On 2023/9/7 0:08, Arnaldo Carvalho de Melo wrote:
> Em Mon, Sep 04, 2023 at 02:33:34AM +0000, Yang Jihong escreveu:
>> User space tasks can migrate between CPUs, track sideband events for all
>> CPUs.
>>
>> The specific scenarios are as follows:
>>
>> CPU0 CPU1
>> perf record -C 0 start
>> taskA starts to be created and executed
>> -> PERF_RECORD_COMM and PERF_RECORD_MMAP
>> events only deliver to CPU1
>> ......
>> |
>> migrate to CPU0
>> |
>> Running on CPU0 <----------/
>> ...
>>
>> perf record -C 0 stop
>>
>> Now perf samples the PC of taskA. However, perf does not record the
>> PERF_RECORD_COMM and PERF_RECORD_COMM events of taskA.
>> Therefore, the comm and symbols of taskA cannot be parsed.
>>
>> The sys_perf_event_open invoked is as follows:
>>
>> # perf --debug verbose=3 record -e cpu-clock -C 1 true
>> <SNIP>
>> Opening: cpu-clock
>> ------------------------------------------------------------
>> perf_event_attr:
>> type 1 (PERF_TYPE_SOFTWARE)
>> size 136
>> config 0 (PERF_COUNT_SW_CPU_CLOCK)
>> { sample_period, sample_freq } 4000
>> sample_type IP|TID|TIME|CPU|PERIOD|IDENTIFIER
>> read_format ID|LOST
>> disabled 1
>> inherit 1
>> freq 1
>> sample_id_all 1
>> exclude_guest 1
>> ------------------------------------------------------------
>> sys_perf_event_open: pid -1 cpu 1 group_fd -1 flags 0x8 = 5
>> Opening: dummy:u
>> ------------------------------------------------------------
>> perf_event_attr:
>> type 1 (PERF_TYPE_SOFTWARE)
>> size 136
>> config 0x9 (PERF_COUNT_SW_DUMMY)
>> { sample_period, sample_freq } 1
>> sample_type IP|TID|TIME|CPU|IDENTIFIER
>> read_format ID|LOST
>> inherit 1
>> exclude_kernel 1
>> exclude_hv 1
>> mmap 1
>> comm 1
>> task 1
>> sample_id_all 1
>> exclude_guest 1
>> mmap2 1
>> comm_exec 1
>> ksymbol 1
>> bpf_event 1
>> ------------------------------------------------------------
>> sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8 = 6
>> sys_perf_event_open: pid -1 cpu 1 group_fd -1 flags 0x8 = 7
>> sys_perf_event_open: pid -1 cpu 2 group_fd -1 flags 0x8 = 9
>> sys_perf_event_open: pid -1 cpu 3 group_fd -1 flags 0x8 = 10
>> sys_perf_event_open: pid -1 cpu 4 group_fd -1 flags 0x8 = 11
>> sys_perf_event_open: pid -1 cpu 5 group_fd -1 flags 0x8 = 12
>> sys_perf_event_open: pid -1 cpu 6 group_fd -1 flags 0x8 = 13
>> sys_perf_event_open: pid -1 cpu 7 group_fd -1 flags 0x8 = 14
>> <SNIP>
>>
>> Changes since_v7:
>> - The condition for requiring system_wide sideband is changed to
>> "as long as a non-dummy event exists" (patch4).
>> - Modify the corresponding test case to record only dummy event (patch6).
>> - Thanks to tested-by tag from Ravi, but because the solution is modified,
>> the tested-by tag of Ravi is not added to this version.
>>
>> Changes since_v6:
>> - Patch1:
>> 1. No change.
>> 2. Keep Acked-by tag from Adrian.
>> - Patch2:
>> 1. Update commit message as suggested by Ian.
>> 2. Keep Acked-by tag from Adrian because code is not modified.
>> - Patch3:
>> 1. Update comment as suggested by Ian.
>> 2. Merge original patch5 ("perf test: Update base-record & system-wide-dummy attr") as suggested by Ian.
>> 3. Only merge commit, keep Acked-by tag from Adrian.
>> - Patch4:
>> 1. No change. Because Adrian recommends not changing the function name.
>> 2. Keep Acked-by tag from Adrian.
>> - Patch5:
>> 1. Add cleanup on trap function as suggested by Ian.
>> 2. Remove Tested-by tag from Adrian because the script is modified.
>> - Patch6:
>> 1. Add Reviewed-by tag from Ian.
>
> I'm in doubt about these Acked-by/Reviewed-by tags, do they still stand? They are
> not in the latest series, can you please check?
Uh, uh. Because several reviewers have different opinions on the
solution, I modified it several times.
Now v8 patchset is different from the previous versions.
I only keep the Acked-by/Reviewed-by tags of patches that are not
modified. For patches that have modified the code, I remove the tags.
Therefore, please refer to the v8 series for Acked-by/Reviewed-by tags.
This version needs to be confirmed by reviewers.
Thanks,
Yang
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