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Re: CVS commit: src
Le 10/03/2017 à 19:01, Valery Ushakov a écrit :
On Fri, Mar 10, 2017 at 13:09:11 +0000, Maxime Villard wrote:
Module Name: src
Committed By: maxv
Date: Fri Mar 10 13:09:11 UTC 2017
src/usr.bin/pmc: pmc.1 pmc.c
Switch to per-CPU PMC results, and completely rewrite the pmc(1) tool. Now
the PMCs are system-wide, fine-grained and more tunable by the user.
We don't do application tracking, since it would require to store the PMC
values in mdproc and starting/stopping the counters on each context switch.
While this doesn't seem to be particularly difficult to achieve, I don't
think it is really interesting; and if someone really wants to measure
the performance of an application, they can simply schedctl it to a cpu
and look at the PMC results for this cpu.
How does that affects the MI pmc(9) API?
It does not; x86 uses a MD sysarch which is intentionally opaque and
undocumented. PMCs are in many ways highly CPU-specific, and MD sysarches are
easier to maintain. I would also add that no one is interested in having a
common API for such features, as long as there is at least one tool that can
correctly use MD entries and display results.
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