linux-kernel - Re: [PATCH] module: ppc64 module CRC relocation fix causes perf issues

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Date:	Fri, 19 Jul 2013 17:59:30 -0500
From:	Scott Wood <scottwood@...escale.com>
To:	Anton Blanchard <anton@...ba.org>
CC:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Neil Horman <nhorman@...driver.com>,
	<linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] module: ppc64 module CRC relocation fix causes perf
 issues

On 07/17/2013 11:00:45 PM, Anton Blanchard wrote:
> 
> Hi Scott,
> 
> > What specifically should I do to test it?
> 
> Could you double check perf annotate works? I'm 99% sure it will but
> that is what was failing on ppc64.

I'm not really sure what it's supposed to look like when "perf  
annotate" works.  It spits a bunch of unreadable[1] dark-blue-on-black  
assembly code at me, all with "0.00 :" in the left column.

Oh, wait -- some lines have "100.00 : " on the left, in  
even-more-unreadable dark-red-on-black.

Apart from the annoying colors, is there anything specific I should be  
looking for?  Some sort of error message, or output that actually makes  
sense?

I've attached the output from "perf annotate" and "perf report".   
perf.data was generated by "perf record find /usr > /dev/null" on an  
NFS root (which took a few seconds to complete), so the large amount of  
__alloc_skb makes some sense, but the way perf annotate shows 100% on  
one instruction in each function seems odd.

-Scott

[1] ...unless I crank the brightness up on my monitor to the point  
where whites are blinding, or redirect the output to a file so the  
colors go away.
View attachment "annotate" of type "text/plain" (36449 bytes)

View attachment "report" of type "text/plain" (526 bytes)