Re: [RFC/PATCHSET 0/6] perf tools: Support dynamic sort keys for tracepoints (v1)

[Namhyung Kim <namhyung@kernel.org>]

Hi David and Arnaldo,

On Mon, Dec 14, 2015 at 03:32:06PM -0700, David Ahern wrote:
> On 12/14/15 10:47 AM, Arnaldo Carvalho de Melo wrote:
> >>With dynamic sort keys, you can use <event.field> as a sort key.  Those
> >>dynamic keys are checked and created on demand.  For instance, below is
> >>to sort by next_pid field on the same data file.
> >>
> >>   $ perf report -s comm,sched:sched_switch.next_pid --stdio
> >>   ...
> >>   # Overhead  Command            next_pid
> >>   # ........  ...............  ..........
> >>   #
> >>       21.23%  transmission-gt           0
> >>       20.86%  swapper               17773
> >>        6.62%  netctl-auto               0
> >>        5.25%  swapper                 109
> >>        5.21%  kworker/0:1H              0
> >>        1.98%  Xephyr                    0
> >>        1.98%  swapper                6524
> >>        1.98%  swapper               27478
> >>        1.37%  swapper               27476
> >>        1.17%  swapper                 233
> >>
> >>Multiple dynamic sort keys are also supported:
> >>
> >>   $ perf report -s comm,sched:sched_switch.next_pid,sched:sched_switch.next_comm --stdio
> >>   ...
> >>   # Overhead  Command            next_pid         next_comm
> >>   # ........  ...............  ..........  ................
> >>   #
> >>       20.86%  swapper               17773   transmission-gt
> >>        9.64%  transmission-gt           0         swapper/0
> >>        9.16%  transmission-gt           0         swapper/2
> >>        5.25%  swapper                 109      kworker/0:1H
> >>        5.21%  kworker/0:1H              0         swapper/0
> >>        2.14%  netctl-auto               0         swapper/2
> >>        1.98%  netctl-auto               0         swapper/0
> >>        1.98%  swapper                6524            Xephyr
> >>        1.98%  swapper               27478       netctl-auto
> >>        1.78%  transmission-gt           0         swapper/3
> >>        1.53%  Xephyr                    0         swapper/0
> >>        1.29%  netctl-auto               0         swapper/1
> >>        1.29%  swapper               27476       netctl-auto
> >>        1.21%  netctl-auto               0         swapper/3
> >>        1.17%  swapper                 233    irq/33-iwlwifi
> >>
> >>Note that pid 0 exists for each cpu so have comm of 'swapper/N'.
> >
> >>This is available on 'perf/dynamic-sort-v1' branch in my tree
> >>
> >>   git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
> >>
> >>Any comments are welcome, thanks!
> >>Namhyung
> >
> >I'll look at the patches for style, but the idea is so nice and natural
> >I thought about blind merging it :-)

Hehe, thanks!


> 
> yes, that is a cool feature.
> 
> For scheduling tracepoints the analysis could be added to perf-sched to ease
> the burden of the command line syntax.

Yes, the existing tracepoints analysis command might use or wrap it.

For command line syntax, I think it'd be better to provide shorter way
to identify the events - like (non-ambiguous) substring match or
positional parameter (e.g. %1 for first event).

For example, the last example above can be:

  $ perf report -s comm,switch.next_pid,switch.next_comm

or

  $ perf report -s comm,%1.next_pid,%1.next_comm


Thanks,
Namhyung