linux-kernel - Re: [patch] Performance Counters for Linux, v2

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Message-ID: <OF9822E5EF.E1B46155-ON87257519.002E51BD-88257519.002EF09B@us.ibm.com>
Date:	Mon, 8 Dec 2008 00:32:41 -0800
From:	Corey J Ashford <cjashfor@...ibm.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Arjan van de Veen <arjan@...radead.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Eric Dumazet <dada1@...mosbay.com>,
	David Miller <davem@...emloft.net>,
	Stephane Eranian <eranian@...glemail.com>,
	Peter Anvin <hpa@...or.com>, linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-kernel-owner@...r.kernel.org,
	Paul Mackerras <paulus@...ba.org>,
	Robert Richter <robert.richter@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [patch] Performance Counters for Linux, v2

linux-kernel-owner@...r.kernel.org wrote on 12/07/2008 05:22:12 PM:
[snip]
> 
> The other big change is the support of virtual task counters via counter 

> scheduling: a task can specify more counters than there are on the CPU, 
> the kernel will then schedule the counters periodically to spread out hw 

> resources. So for example if a task starts 6 counters on a CPU that has 
> only two hardware counters, it still gets this output:
> 
>  counter[0 cycles              ]:   5204680573 , delta:   1733680843 
events
>  counter[1 instructions        ]:   1364468045 , delta:    454818351 
events
>  counter[2 cache-refs          ]:        12732 , delta:         4399 
events
>  counter[3 cache-misses        ]:         1009 , delta:          336 
events
>  counter[4 branch-instructions ]:    125993304 , delta:     42006998 
events
>  counter[5 branch-misses       ]:         1946 , delta:          649 
events
>

Hello Ingo,

I posted some questions about this capability in your proposal on LKML, 
but I wasn't able to get the reply threaded in properly.  Could you take a 
look at this post, please?

http://lkml.org/lkml/2008/12/5/299

Thanks for your consideration,

- Corey

Corey Ashford
Software Engineer
IBM Linux Technology Center, Linux Toolchain
Beaverton, OR 
503-578-3507 
cjashfor@...ibm.com
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