Re: [PATCH] perf report: show sort_order in title

[Du, Changbin]

On Mon, Mar 13, 2017 at 11:57:18AM -0300, Arnaldo Carvalho de Melo wrote:
> > I'll just rename this to use the tools/perf/ style for such functions,
> > making it:
> > 
> >     static int hists__scnprintf_sort_fields(hists, buf, size)
> 
> But then, while testing, 
> 
> Before:
> 
>   $ perf report
>   Samples: 405  of event 'cycles', Event count (approx.): 101733003
>   Overhead  Command          Shared Object                        Symbol
>     11.15%  swapper          [kernel.vmlinux]                     [k] 
> intel_idle
>      3.00%  firefox          libxul.so                            [.] 
> 0x0000000001298b8d
>      1.74%  swapper          [kernel.vmlinux]                     [k] 
> update_blocked_averages
>      1.69%  qemu-system-x86  [kernel.vmlinux]                     [k] __fget
>      1.18%  swapper          [kernel.vmlinux]                     [k] 
> update_wall_time
> 
>   Tip: Save output of perf stat using: perf stat record <target workload>
> 
> After:
> 
>   $ perf report
>   Samples: 405  of event 'cycles', Event count (approx.): 101733003, Sort by: 
> Children,Overhead,Command,Shared Object,Symbol
>   Overhead  Command          Shared Object                        Symbol
>     11.15%  swapper          [kernel.vmlinux]                     [k] 
> intel_idle
>      3.00%  firefox          libxul.so                            [.] 
> 0x0000000001298b8d
>      1.74%  swapper          [kernel.vmlinux]                     [k] 
> update_blocked_averages
>      1.69%  qemu-system-x86  [kernel.vmlinux]                     [k] __fget
>      1.18%  swapper          [kernel.vmlinux]                     [k] 
> update_wall_time
> 
> 
> I see now duplication of info, where is the value? Can you show the usecase in
> a compelling way?
> 
> - Arnaldo

Thanks for trying. The key idea is to show how does the data sort, especially
the first sort key. When I use some GUI based perf tool, I can see how
my data is sorted by checking the report header status. I think this is
a good for browser.

You are right, the info is duplicated. I got another idea that we show a '↓' at
the header string and only for the first sort key. What do you think?

$ perf report
   Samples: 405  of event 'cycles', Event count (approx.): 101733003
   ↓Overhead  Command          Shared Object                        Symbol
     11.15%  swapper          [kernel.vmlinux]                     [k] 
intel_idle
      3.00%  firefox          libxul.so                            [.] 
0x0000000001298b8d
      1.74%  swapper          [kernel.vmlinux]                     [k] 
update_blocked_averages

Another idea I want to add is to support dynamic sorting. For me, I use perf to
analysing entire system performance, and the data is very large. Then sometimes
it take as long as ~10 minitues to read perf data. So I think if we can change
sort w/o reload data will be good.

-- 
Thanks,
Changbin Du

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