Re: [PATCH] perf script: print cgroup on the same line as comm

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Aug 08, 2023 at 10:44:26AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Mon, Aug 07, 2023 at 11:02:01AM -0700, Ivan Babrou escreveu:
> > On Fri, Jul 28, 2023 at 10:57 AM Ian Rogers <irogers@google.com> wrote:
> > > On Fri, Jul 28, 2023 at 10:42 AM Ivan Babrou <ivan@cloudflare.com> wrote:
> > > > On Mon, Jul 17, 2023 at 5:07 PM Ivan Babrou <ivan@cloudflare.com> wrote:
> > > > > Commit 3fd7a168bf51 ("perf script: Add 'cgroup' field for output")
> > > > > added support for printing cgroup path in perf script output.
> 
> > > > > It was okay if you didn't want any stacks:
> 
> > > > >     $ sudo perf script --comms jpegtran:23f4bf -F comm,tid,cpu,time,cgroup
> > > > >     jpegtran:23f4bf 3321915 [013] 404718.587488:  /idle.slice/polish.service
> > > > >     jpegtran:23f4bf 3321915 [031] 404718.592073:  /idle.slice/polish.service
> 
> > > > > With stacks it gets messier as cgroup is printed after the stack:
> 
> > > > >     $ perf script --comms jpegtran:23f4bf -F comm,tid,cpu,time,cgroup,ip,sym
> > > > >     jpegtran:23f4bf 3321915 [013] 404718.587488:
> > > > >                     5c554 compress_output
> > > > >                     570d9 jpeg_finish_compress
> > > > >                     3476e jpegtran_main
> > > > >                     330ee jpegtran::main
> > > > >                     326e2 core::ops::function::FnOnce::call_once (inlined)
> > > > >                     326e2 std::sys_common::backtrace::__rust_begin_short_backtrace
> > > > >     /idle.slice/polish.service
> > > > >     jpegtran:23f4bf 3321915 [031] 404718.592073:
> > > > >                     8474d jsimd_encode_mcu_AC_first_prepare_sse2.PADDING
> > > > >                 55af68e62fff [unknown]
> > > > >     /idle.slice/polish.service
> > > > >
> > > > > Let's instead print cgroup on the same line as comm:
> > > > >
> > > > >     $ perf script --comms jpegtran:23f4bf -F comm,tid,cpu,time,cgroup,ip,sym
> > > > >     jpegtran:23f4bf 3321915 [013] 404718.587488:  /idle.slice/polish.service
> > > > >                     5c554 compress_output
> > > > >                     570d9 jpeg_finish_compress
> > > > >                     3476e jpegtran_main
> > > > >                     330ee jpegtran::main
> > > > >                     326e2 core::ops::function::FnOnce::call_once (inlined)
> > > > >                     326e2 std::sys_common::backtrace::__rust_begin_short_backtrace
> > > > >
> > > > >     jpegtran:23f4bf 3321915 [031] 404718.592073:  /idle.slice/polish.service
> > > > >                     8474d jsimd_encode_mcu_AC_first_prepare_sse2.PADDING
> > > > >                 55af68e62fff [unknown]
> > > > >
> > > > > Signed-off-by: Ivan Babrou <ivan@cloudflare.com>
> > > > > Fixes: 3fd7a168bf51 ("perf script: Add 'cgroup' field for output")
> 
> > > This change makes sense to me. Namhyung, wdyt?
>  
> > Hi Namhyung,
> > 
> > This is a really trivial patch and it would be good to get a word from you.
> 
> Hi, this solves the case for cgroup and I think it should be merged, but
> what about the other fields that are being printed after the callchain
> gets printed?
> 
> I looked and we would have to introduce a __sample__fprintf_sym that
> didn't call sample__fprintf_callchain and use it in perf script's
> process_event() then later call sample__fprintf_callchain after all the
> fields that print on the same line.

Nah, or simply moving sample__fprintf_sym() to the end of that function.

- Arnaldo
 
> Anyway, Namhyung, can I have your Acked-by for this patch to move things
> forward at least for cgroups?