linux-kernel - Re: [PATCH] perf dso: Fix dso comparison

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Message-ID: <20200324132258.GX1534489@krava>
Date:   Tue, 24 Mar 2020 14:22:58 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Cc:     acme@...nel.org, linux-kernel@...r.kernel.org, namhyung@...nel.org,
        mark.rutland@....com, naveen.n.rao@...ux.vnet.ibm.com
Subject: Re: [PATCH] perf dso: Fix dso comparison

On Tue, Mar 24, 2020 at 06:07:23PM +0530, Ravi Bangoria wrote:

SNIP

> > 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?

the above behaviour is something I'd expect from 'dso'
sort key to do - separate out different dsos, even with
the same name

jirka