linux-kernel - Re: [PATCH] perf report: Fix input reload/switch functionality

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Message-ID: <20d97acb-bcf8-481e-a898-a13580c566b0@linaro.org>
Date: Mon, 13 Jan 2025 15:19:49 +0000
From: James Clark <james.clark@...aro.org>
To: Dmitry Vyukov <dvyukov@...gle.com>
Cc: linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
 namhyung@...nel.org, irogers@...gle.com
Subject: Re: [PATCH] perf report: Fix input reload/switch functionality



On 10/01/2025 12:19 pm, Dmitry Vyukov wrote:
> On Thu, 9 Jan 2025 at 15:50, James Clark <james.clark@...aro.org> wrote:
>> On 08/01/2025 3:35 pm, Dmitry Vyukov wrote:
>>> On Wed, 8 Jan 2025 at 16:23, James Clark <james.clark@...aro.org> wrote:
>>>>
>>>> On 08/01/2025 6:36 am, Dmitry Vyukov wrote:
>>>>> Currently the code checks that there is no "ipc" in the sort order
>>>>> and add an ipc string. This will always error out on the second pass
>>>>> after input reload/switch, since the sort order already contains "ipc".
>>>>> Do the ipc check/fixup only on the first pass.
>>>>>
>>>>
>>>> Hi Dmitry,
>>>>
>>>> A reproducer with before and after behavior might be helpful for the review.
>>>>
>>>> It might be unrelated to your change here, but the input switch thing
>>>> didn't seem to do anything for me. If I record two files, open the first
>>>> one, press S and select the second file nothing seems to change. I
>>>> assumed it would show the other file but nothing changes?
>>>>
>>>>     $ perf record -- true
>>>>     $ perf record -o 2.data -- ls
>>>>     $ perf report
>>>>     S key
>>>>     load 2.data
>>>
>>> Yes, sure. This needs "--sort symbol":
>>>
>>> perf report --sort symbol
>>>
>>> then press 's', select file, and it terminates.
>>>
>>> Affects fewer cases then I initially assumed, since I happened to run
>>> with "--sort symbol" when I discovered it.
>>>
>>>
>>
>> Ah yeah I can reproduce the bug with --sort, which is fixed by the
>> patch. But 's' doesn't actually reload a new histogram for me, I just
>> get the original file again. Maybe I'm misunderstanding what 's' is
>> supposed to do?
> 
> As far as I understand, 's' allows you to select and load a new
> profile w/o existing (fwiw, if you select a different file). If the

By 'without existing' do you mean running perf report with no perf.data 
file? It won't run like that it just says "failed to open perf.data"

> file has changed, I guess you can also reload it and see the changes.
> 

I wasn't able to make that work. How do you reload? If I change screen 
between different events I still get the old file and I didn't see 
'reload' mentioned in the keybinding popup.

I suppose my point is maybe it's not worth fixing the sort order bug if 
we can just remove input file switching. The behavior doesn't seem any 
different to v5.8 in case its a regression. Maybe I'm just doing 
something wrong though.

> 
>>>>> Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
>>>>> Fixes: ec6ae74fe8f0 ("perf report: Display average IPC and IPC coverage per symbol")
>>>>    > Cc: Namhyung Kim <namhyung@...nel.org>> Cc: Ian Rogers
>>>> <irogers@...gle.com>
>>>>> Cc: linux-perf-users@...r.kernel.org
>>>>> Cc: linux-kernel@...r.kernel.org
>>>>> ---
>>>>>     tools/perf/builtin-report.c | 30 ++++++++++++++++--------------
>>>>>     1 file changed, 16 insertions(+), 14 deletions(-)
>>>>>
>>>>> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
>>>>> index 048c91960ba91..42d7dfdf07d9b 100644
>>>>> --- a/tools/perf/builtin-report.c
>>>>> +++ b/tools/perf/builtin-report.c
>>>>> @@ -1721,22 +1721,24 @@ int cmd_report(int argc, const char **argv)
>>>>>                 symbol_conf.annotate_data_sample = true;
>>>>>         }
>>>>>
>>>>> -     if (sort_order && strstr(sort_order, "ipc")) {
>>>>> -             parse_options_usage(report_usage, options, "s", 1);
>>>>> -             goto error;
>>>>> -     }
>>>>> -
>>>>> -     if (sort_order && strstr(sort_order, "symbol")) {
>>>>> -             if (sort__mode == SORT_MODE__BRANCH) {
>>>>> -                     snprintf(sort_tmp, sizeof(sort_tmp), "%s,%s",
>>>>> -                              sort_order, "ipc_lbr");
>>>>> -                     report.symbol_ipc = true;
>>>>> -             } else {
>>>>> -                     snprintf(sort_tmp, sizeof(sort_tmp), "%s,%s",
>>>>> -                              sort_order, "ipc_null");
>>>>> +     if (last_key != K_SWITCH_INPUT_DATA) {
>>>>> +             if (sort_order && strstr(sort_order, "ipc")) {
>>>>> +                     parse_options_usage(report_usage, options, "s", 1);
>>>>> +                     goto error;
>>>>>                 }
>>>>>
>>>>> -             sort_order = sort_tmp;
>>>>> +             if (sort_order && strstr(sort_order, "symbol")) {
>>>>> +                     if (sort__mode == SORT_MODE__BRANCH) {
>>>>> +                             snprintf(sort_tmp, sizeof(sort_tmp), "%s,%s",
>>>>> +                                      sort_order, "ipc_lbr");
>>>>> +                             report.symbol_ipc = true;
>>>>> +                     } else {
>>>>> +                             snprintf(sort_tmp, sizeof(sort_tmp), "%s,%s",
>>>>> +                                      sort_order, "ipc_null");
>>>>> +                     }
>>>>> +
>>>>> +                     sort_order = sort_tmp;
>>>>> +             }
>>>>>         }
>>>>>
>>>>>         if ((last_key != K_SWITCH_INPUT_DATA && last_key != K_RELOAD) &&
>>>>>
>>>>> base-commit: 09a0fa92e5b45e99cf435b2fbf5ebcf889cf8780
>>>>
>>