Re: [RFC PATCH] perf_core: provide a kernel-internal interface to get to performance counters

From: john smith
Date: Fri Feb 05 2010 - 12:59:41 EST


> So this patch got accepted into mainline a while ago,
> without a user
> ever beeing presented, nevermind actually included in
> mainline. Time
> to revert providing these useless exports and dead code?

I think kernel perf api is very useful for improving kernel (modules) performance, and of course, for this purpose their usage won't make it into the distribution code.
I started to use them but still I would like to see an example showing its full potential (cpufreq was proposed).

Imagine moving structure's fields around for increasing cache performance, the general perf counters are, hmm, too general when we need to monitor only some code sections (after being identified using the global perf counters/tool).

John

--- On Fri, 2/5/10, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:

> From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> Subject: Re: [RFC PATCH] perf_core: provide a kernel-internal interface to get to performance counters
> To: "Arjan van de Ven" <arjan@xxxxxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx, mingo@xxxxxxx, peterz@xxxxxxxxxxxxx, "Frederic Weisbecker" <fweisbec@xxxxxxxxx>
> Date: Friday, February 5, 2010, 7:47 AM
> On Fri, Sep 25, 2009 at 12:25:56PM
> +0200, Arjan van de Ven wrote:
> > >From 5db5cd76f3c16c9f6093f54d1ccfb97d04b9a1ca Mon
> Sep 17 00:00:00 2001
> > From: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
> > Date: Fri, 25 Sep 2009 12:20:57 +0200
> > Subject: [PATCH] perf_core: provide a kernel-internal
> interface to get to performance counters
>
> So this patch got accepted into mainline a while ago,
> without a user
> ever beeing presented, nevermind actually included in
> mainline.  Time
> to revert providing these useless exports and dead code?
>
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