Re: Add top down metrics to perf stat v2

Andi Kleen
2015-12-17T14:01:28Z

On Thu, Dec 17, 2015 at 02:27:58AM -0800, Stephane Eranian wrote:
> > S0-C1 2 4175583320.00 topdown-slots-retired (100.00%)
> > S0-C1 2 1743329246 topdown-recovery-bubbles # 22.22% bad speculation (100.00%)
> > S0-C1 2 6138901193.50 topdown-slots-issued # 46.99% backend bound
> >
> I don't see how this output could be very useful. What matters is the
> percentage in the comments
> and not so much the raw counts because what is the unit? Same remark
> holds for the percentage.
> I think you need to explain or show that this is % of issue slots and
> not cycles.

The events already say slots, not cycles. Except for recovery-bubbles. Could add
-slots there too if you think it's helpful, although it would make the
name very long and may not fit into the column anymore.

>
> > 1.535832673 seconds time elapsed
> >
> > $ perf stat --topdown --topdown --metric-only -I 100 ./BC1s
>
> When I tried from your git tree the --metric-only option was not recognized.

See below.
>
> > 0.100576098 frontend bound retiring bad speculation backend bound
> > 0.100576098 8.83% 48.93% 35.24% 7.00%
> > 0.200800845 8.84% 48.49% 35.53% 7.13%
> > 0.300905983 8.73% 48.64% 35.58% 7.05%
> > ...
> >
> This kind of output is more meaningful and clearer for end-users based
> on my experience
> and you'd like it per-core possibly.

Yes --metric-only is a lot clearer.

per-core is supported and automatically enabled with SMT on.

> > Full tree available in
> > git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-misc perf/top-down-11
>
> That is in the top-down-2 branch instead, I think.

Sorry, typo

The correct branch is perf/top-down-10

I also updated it now with the latest review feedback changes.

top-down-2 is an really old branch that indeed didn't have metric-only.

-Andi

--
ak@linux.intel.com -- Speaking for myself only.