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Subject: Re: [PATCH 0/5] perf stat: Introduce --iiostat mode to provide I/O
 performance metrics
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Andi Kleen <ak@linux.intel.com>
Cc:     linux-kernel@vger.kernel.org, jolsa@redhat.com,
        alexander.shishkin@linux.intel.com, mark.rutland@arm.com,
        namhyung@kernel.org, mingo@redhat.com, peterz@infradead.org,
        Ian Rogers <irogers@google.com>
References: <20201210090340.14358-1-alexander.antonov@linux.intel.com>
 <20201214132828.GD238399@kernel.org>
 <20201215030430.GA1538637@tassilo.jf.intel.com>
 <20201215135849.GD252952@kernel.org>
From:   Alexander Antonov <alexander.antonov@linux.intel.com>
Message-ID: <bea68d24-8b21-c4a7-5cd4-14d31b484222@linux.intel.com>
Date:   Sun, 20 Dec 2020 20:23:21 +0300
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On 12/15/2020 4:58 PM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Dec 14, 2020 at 07:04:30PM -0800, Andi Kleen escreveu:
>>> My first thought was: Why not have a 'perf iiostat' subcommand?
>   
>> Same would apply to a lot of options in perf stat.
>   
>> I guess you could add some aliases to "perf" that give shortcuts
>> for common perf stat command lines.
> Yeah, and we have a mechanism for that, that was exercised only in the
> 'perf archive' case:
>
> ~/libexec/perf-core/perf-archive
>
> I tried this and it works:
>
> [root@five ~]# ls -la ~/bin/perf
> lrwxrwxrwx. 1 root root 19 Feb 18  2020 /root/bin/perf -> /home/acme/bin/perf
> [root@five ~]# vim ~acme/libexec/perf-core/perf-cgtop
> [root@five ~]# chmod +x ~acme/libexec/perf-core/perf-cgtop
> [root@five ~]# cat ~acme/libexec/perf-core/perf-cgtop
> perf top --hierarchy --all-cgroups -s cgroup,dso,sym $*
> [root@five ~]# perf cgtop
> [root@five ~]#
>
> use 'e' to expand collapse the current level (+ -> -), 'E'/'C' to
> expand/collapse all levels.
>
> 'perf help' doesn't show it, which is a shame, I'll add support for it
> to traverse ~/libexec/perf-core/perf-* and get the first non interpreter
> comment line as a description for the command, so to add a new one is
> just a matter of dropping a shell + man page, no need to change the perf
> binary.
>
>
> To test that '$*' at the end:
>
> [root@five ~]# perf cgtop -U
>
> I.e.:
>
> [acme@five perf]$ perf top -h -U
>
>   Usage: perf top [<options>]
>
>      -U, --hide_user_symbols
>                            hide user symbols
>
> [acme@five perf]$
>
> And it works, just kernel level samples grouped in an hierarchy, first
> cgroup, then dso, then the symbol.
>
> Also, using this with the 'P' hotkey:
>
> [root@five ~]# perf cgtop --percent-limit 1
>
> Shows how it looks like:
>
> [root@five ~]# cat perf.hist.0
> -  86.77%        /user.slice/user-1000.slice/session-2.scope
>     -  36.18%        [kernel]
>            2.24%        [k] unmap_page_range
>            1.15%        [k] clear_page_rep
>            1.10%        [k] add_mm_counter_fast
>            1.03%        [k] alloc_set_pte
>            1.03%        [k] handle_mm_fault
>     -  17.65%        libc-2.32.so
>            2.04%        [.] _int_malloc
>            1.82%        [.] __memmove_avx_unaligned_erms
>            1.48%        [.] __strlen_avx2
>            1.13%        [.] _int_free
>            1.12%        [.] malloc
>     -   8.09%        make
>            1.65%        [.] jhash_string
>            1.05%        [.] hash_find_slot
>     -   6.90%        ld-2.32.so
>            2.03%        [.] do_lookup_x
>            1.49%        [.] _dl_lookup_symbol_x
>     -   4.78%        cc1
>     -   4.60%        libperl.so.5.32.0
>     -   2.86%        bash
>     -   1.98%        libselinux.so.1
>     -   1.61%        libpython2.7.so.1.0
>     -   1.06%        libpcre2-8.so.0.10.0
> -   9.17%        /user.slice/user-1000.slice/session-4.scope
>     -   4.66%        perf
>     -   2.40%        libc-2.32.so
>     -   1.82%        [kernel]
> -   4.04%        /
>     -   4.02%        [kernel]
> [root@five ~]#
>
> So 'perf iiostat' would become:
>
> [root@five ~]# cat ~acme/libexec/perf-core/perf-iiostat
> perf stat --iiostat $*
> [root@five ~]#
>
> There are parameters to that '--iiostat' in the current patchset that
> may complicates this tho, with some changes I guess we get what we want.
>
> - Arnaldo

Hello Arnaldo,
Sorry for delayed response.

This is the interesting approach to get shorter command. Thank you for the
explanation. I will update the patchset.

- Alexander