From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
To: Jiri Olsa <jolsa@redhat.com>
Cc: acme@kernel.org, linux-kernel@vger.kernel.org,
namhyung@kernel.org, mark.rutland@arm.com,
naveen.n.rao@linux.vnet.ibm.com,
Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Subject: Re: [PATCH] perf dso: Fix dso comparison
Date: Tue, 24 Mar 2020 18:07:23 +0530 [thread overview]
Message-ID: <3cf2bd1b-e1c2-f82f-a06a-ce0d5e4b5eac@linux.ibm.com> (raw)
In-Reply-To: <20200324104843.GS1534489@krava>
On 3/24/20 4:18 PM, Jiri Olsa wrote:
> On Tue, Mar 24, 2020 at 09:54:24AM +0530, Ravi Bangoria wrote:
>> Perf gets dso details from two different sources. 1st, from builid
>> headers in perf.data and 2nd from MMAP2 samples. Dso from buildid
>> header does not have dso_id detail. And dso from MMAP2 samples does
>> not have buildid information. If detail of the same dso is present
>> at both the places, filename is common.
>>
>> Previously, __dsos__findnew_link_by_longname_id() used to compare only
>> long or short names, but Commit 0e3149f86b99 ("perf dso: Move dso_id
>> from 'struct map' to 'struct dso'") also added a dso_id comparison.
>> Because of that, now perf is creating two different dso objects of the
>> same file, one from buildid header (with dso_id but without buildid)
>> and second from MMAP2 sample (with buildid but without dso_id).
>>
>> This is causing issues with archive, buildid-list etc subcommands. Fix
>> this by comparing dso_id only when it's present. And incase dso is
>> present in 'dsos' list without dso_id, inject dso_id detail as well.
>>
>> Before:
>>
>> $ sudo ./perf buildid-list -H
>> 0000000000000000000000000000000000000000 /usr/bin/ls
>> 0000000000000000000000000000000000000000 /usr/lib64/ld-2.30.so
>> 0000000000000000000000000000000000000000 /usr/lib64/libc-2.30.so
>>
>> $ ./perf archive
>> perf archive: no build-ids found
>>
>> After:
>>
>> $ ./perf buildid-list -H
>> b6b1291d0cead046ed0fa5734037fa87a579adee /usr/bin/ls
>> 641f0c90cfa15779352f12c0ec3c7a2b2b6f41e8 /usr/lib64/ld-2.30.so
>> 675ace3ca07a0b863df01f461a7b0984c65c8b37 /usr/lib64/libc-2.30.so
>>
>> $ ./perf archive
>> Now please run:
>>
>> $ tar xvf perf.data.tar.bz2 -C ~/.debug
>>
>> wherever you need to run 'perf report' on.
>>
>> Reported-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
>
> looks good, do we need to add the dso_id check to sort__dso_cmp?
I guess with different filename there is no need to compare dso_id.
But for same filename, adding dso_id cmp will separate out the
samples:
Ex, Without dso_id compare:
$ ./perf report -s dso,dso_size -v
66.63% /home/ravi/a.out 4096
33.36% /home/ravi/Workspace/linux/tools/perf/a.out 4096
$ ./perf report -s dso,dso_size
99.99% a.out 4096
With below diff:
- return strcmp(dso_name_l, dso_name_r);
+ ret = strcmp(dso_name_l, dso_name_r);
+ if (ret)
+ return ret;
+ else
+ return dso__cmp_id(dso_l, dso_r);
$ ./perf report -s dso,dso_size
99.99% a.out 4096
33.36% a.out 4096
though, the o/p also depends which other sort keys are used along
with dso key. Do you think this change makes sense?
Ravi
next prev parent reply other threads:[~2020-03-24 12:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 4:24 [PATCH] perf dso: Fix dso comparison Ravi Bangoria
2020-03-24 10:48 ` Jiri Olsa
2020-03-24 12:37 ` Ravi Bangoria [this message]
2020-03-24 13:22 ` Jiri Olsa
2020-03-24 13:42 ` Arnaldo Carvalho de Melo
2020-03-24 13:42 ` Ravi Bangoria
2020-03-24 13:00 ` Arnaldo Carvalho de Melo
2020-03-24 13:20 ` Jiri Olsa
2020-03-24 13:21 ` Arnaldo Carvalho de Melo
2020-03-24 13:44 ` Naveen N. Rao
2020-04-04 8:41 ` [tip: perf/urgent] " tip-bot2 for Ravi Bangoria
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