Re: [Gems-users] Coherence misses

[Dan Gibson <degibson@xxxxxxxx>]

Total_misses are L2 misses -- probably not what you want. Towards the bottom of the stats file, there should be a summary of protocol transitions. Depending on your protocol, you should be able to get a notion of how many 'coherence misses' there are.

Regards,
Dan

On Thu, Mar 19, 2009 at 12:22 AM, Edward Lee <edwl202@xxxxxxxxx> wrote:

Let me try to summarize what I am trying to do, maybe I can get a feedback this time.

I am running FFT on an 8 processor SMP target using MOSI_SMP_bcast cache coherence protocol. I used the warm caches and loaded Ruby for the main computation only. And my purpose is to somehow measure the overhead of maintaining coherent caches. Accordingly, I would like to isolate different types of cache misses especially the coherence misses.

I got the ruby.stats file but I am not sure if I can use this output directly for what I need. I have the total misses as copied from my ruby.stats file like this:

Total_misses: 127314
total_misses: 127314 [ 22540 16951 16571 16564 12979 12803 12781 16125 ]
user_misses: 96467 [ 13183 12989 12742 12637 11184 11161 11144 11427 ]
supervisor_misses: 30847 [ 9357 3962 3829 3927 1795 1642 1637 4698 ]

I didn't paste the whole stats as it is quite large but my question is whether there is any information already existing in the ruby-stats file that can isolate different cache misses (global count is fine)? Or should I try to modify the profiler code to get this info?

Also, I have the number of misses but I don't see the total number of accesses in that section? So, would it be correct if I use the "Data requests" from "Simics Driver Transaction Stats"? However, the "Request missed" shows 189346 there, bigger than the misses shown above.

I would really appreciate any input on this.

Regards,

Ed

On Sun, Mar 15, 2009 at 12:09 AM, Edward Lee <edwl202@xxxxxxxxx> wrote:

Hi,

I am trying to isolate the cache misses according to their types. So, what would be the best way of differentiating cold, capacity and coherence misses?

Thanks,

Ed

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