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Date: Fri, 2 Jul 2004 01:26:46 +0200
From: bert hubert <ahu@ds9a.nl>
To: "Bryan O'Sullivan" <bos@serpentine.com>
Cc: Mikael.Pettersson@csd.uu.se, linux-kernel@vger.kernel.org, akpm@osdl.org
Subject: Re: perfctr questions
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On Thu, Jul 01, 2004 at 03:19:54PM -0700, Bryan O'Sullivan wrote:

> > I'm trying to test your performance counters stuff, but I can't get it to do
> > anything remotely useful! Probably just me.

Ok, it is working. This is a plot of the number of L2 Address Strobes
counted while scanning a buffer of x bytes: http://ds9a.nl/tmp/strobes.png 

>>From dmesg:
CPU: L1 I cache: 32K, L1 D cache: 32K

Note the sharp rise at 32768 bytes!

int main(int argc, char **argv)
{
        char *memory;
        int len=atoi(argv[1]);
        memory=malloc(len);
        int n, count;
        for(count=0;count<10000;++count) 
                for(n=1;n<len;++n) {    
                        memory[n]++;
                }
}

Script:

for a in $(seq 30000 10 35000) ; do perfex -o log -e 0x00410021 ./null $a ;
echo -n "$a " ; tail -1 log | awk '{print $3}'; done > line

The '21' stands for P6_L2_ADS.

Cool stuff!

Regards,

bert

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