Re: [PATCH] perf, tools, script: Allow adding and removing fields

[Milian Wolff <milian.wolff@kdab.com>]

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On Friday, June 2, 2017 5:48:10 PM CEST Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
> 
> With perf script it is common that we just want to add or remove a field.
> Currently this requires figuring out the long list of default fields and
> specifying them first, and then adding/removing the new field.
> 
> This patch adds a new + - syntax to merely add or remove fields,
> that allows more succint and clearer command lines
> 
> For example to remove the comm field from PMU samples:
> 
> Previously
> 
> perf script -F tid,cpu,time,event,sym,ip,dso,period
> 	    0 [000] 504345.383126:          1 cycles:  ffffffff90060c66
> native_write_msr ([kernel.kallsyms])
> 
> with the new syntax
> 
> perf script -F -comm
> 	    0 [000] 504345.383126:          1 cycles:  ffffffff90060c66
> native_write_msr ([kernel.kallsyms])
> 
> The new syntax cannot be mixed with normal overriding.

Tested-by: Milian Wolff <milian.wolff@kdab.com>

Works a charm.

But I notice that this functionality is missing in other places too. Most 
notably, I would like to be able to configure `perf stat` in a similar way. 
Such that one could do:

perf stat -e +cache-misses

Instead of

perf stat -e <whatever the defaults are>,cache-misses

While at it, I also think it would be tremendously useful to get wildcard 
matching behavior in all perf tools. Currently, I can do:

perf list "topdown-*"

List of pre-defined events (to be used in -e):

  topdown-fetch-bubbles OR cpu/topdown-fetch-bubbles/ [Kernel PMU event]
  topdown-recovery-bubbles OR cpu/topdown-recovery-bubbles/ [Kernel PMU event]
  topdown-slots-issued OR cpu/topdown-slots-issued/  [Kernel PMU event]
  topdown-slots-retired OR cpu/topdown-slots-retired/ [Kernel PMU event]
  topdown-total-slots OR cpu/topdown-total-slots/    [Kernel PMU event]

But I cannot do:

$ perf record -e "topdown-*" ls
event syntax error: 'topdown-*'
                            \___ parser error
Run 'perf list' for a list of valid events

But of course I'm aware that these are all separate issues. But Andi, you seem 
to be working a lot on polishing perf. I'd really appreciate it if you could 
also implement the above two suggestions. Otherwise I'll try to see when I get 
the time to do it myself.

Cheers

-- 
Milian Wolff | milian.wolff@kdab.com | Software Engineer
KDAB (Deutschland) GmbH&Co KG, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt Experts

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