linux-kernel - Re: [PATCH] perf report: Output non-zero offset for decompressed records

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Message-ID: <6ab9dd72-ccac-4ce1-6456-ef7786911639@linux.intel.com>
Date:   Mon, 4 Oct 2021 10:00:52 +0300
From:   "Bayduraev, Alexey V" <alexey.v.bayduraev@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexander Antonov <alexander.antonov@...ux.intel.com>,
        Alexei Budankov <abudankov@...wei.com>,
        Riccardo Mancini <rickyman7@...il.com>
Subject: Re: [PATCH] perf report: Output non-zero offset for decompressed
 records


On 04.10.2021 9:42, Jiri Olsa wrote:
> On Wed, Sep 29, 2021 at 12:14:45PM +0300, Alexey Bayduraev wrote:
>> Print offset of PERF_RECORD_COMPRESSED record instead of zero for
>> decompressed records in raw trace dump (-D option of perf-report):
>>
>> 0x17cf08 [0x28]: event: 9
>>
>> instead of:
>>
>> 0 [0x28]: event: 9
>>
>> The fix is not critical, because currently file_pos for compressed
>> events is used in perf_session__process_event only to show offsets
>> in the raw dump.
> 
> hi,
> I don't mind the change just curious, because I see also:
> 
>   perf_session__process_event
>     perf_session__process_user_event
>       lseek(fd, file_offset, ...
> 
> which is not raw dump as the comment suggests

Hi,

Yes, but this "lseek" only works for user events, whereas the 
PERF_RECORD_COMPRESSED record shouln't contain such events.
Currently, the PERF_RECORD_COMPRESSED container can only pack
kernel events. 

Regards,
Alexey

> 
> thanks,
> jirka
> 
>>
>> This patch was separated from patchset:
>> https://lore.kernel.org/lkml/cover.1629186429.git.alexey.v.bayduraev@linux.intel.com/
>> and was already rewieved.
>>
>> Acked-by: Namhyung Kim <namhyung@...nel.org>
>> Acked-by: Andi Kleen <ak@...ux.intel.com>
>> Reviewed-by: Riccardo Mancini <rickyman7@...il.com>
>> Tested-by: Riccardo Mancini <rickyman7@...il.com>
>> Signed-off-by: Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>
>> ---
>>  tools/perf/util/session.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
>> index 069c2cfdd3be..352f16076e01 100644
>> --- a/tools/perf/util/session.c
>> +++ b/tools/perf/util/session.c
>> @@ -2116,7 +2116,7 @@ fetch_decomp_event(u64 head, size_t mmap_size, char *buf, bool needs_swap)
>>  static int __perf_session__process_decomp_events(struct perf_session *session)
>>  {
>>  	s64 skip;
>> -	u64 size, file_pos = 0;
>> +	u64 size;
>>  	struct decomp *decomp = session->decomp_last;
>>  
>>  	if (!decomp)
>> @@ -2132,7 +2132,7 @@ static int __perf_session__process_decomp_events(struct perf_session *session)
>>  		size = event->header.size;
>>  
>>  		if (size < sizeof(struct perf_event_header) ||
>> -		    (skip = perf_session__process_event(session, event, file_pos)) < 0) {
>> +		    (skip = perf_session__process_event(session, event, decomp->file_pos)) < 0) {
>>  			pr_err("%#" PRIx64 " [%#x]: failed to process type: %d\n",
>>  				decomp->file_pos + decomp->head, event->header.size, event->header.type);
>>  			return -EINVAL;
>> -- 
>> 2.19.0
>>
>