Re: hardware prefetcher events

On Thu, Feb 23, 2012 at 10:16 PM, Ramachandra CN
<cn.ramachandra <at> gmail.com> wrote:
> Hello,
>
> I have some questions related to hardware prefetcher events on Intel Xeon
> processor with the below configuration.
> $ uname -a
> Linux 2.6.34-gentoo-r1 #2 SMP Mon Feb 20 12:07:35 CST 2012 x86_64 Intel(R)
> Xeon(R) CPU E5520  <at>  2.27GHz GenuineIntel GNU/Linux
>
> I am trying to count the number of hardware prefetch events, before and
> after disabling hardware prefetching using BIOS.
> I have followed the steps mentioned in the below link to disable h/w
> prefetching in BIOS.
> http://software.intel.com/en-us/articles/optimizing-application-performance-on-intel-coret-microarchitecture-using-hardware-implemented-prefetchers/
>
Something is not right here.
You processor E5520 is not a Core micro-architecture but Nehalem-EP.
As such, I believe the technique
above to disable HW prefetcher does not apply.

> However I don't see much difference in the values of the counter after h/w
> prefetching is disabled. The counter value remains approximately the same
> before and after disabling h/w prefetching. I also tried
> using "PERF_COUNT_HW_CACHE_L1D:PREFETCH" event. But don't see much
> difference.
> I have used the perf_examples program of libpfm-4.2,.0 as below.
> ./task -e L1D_PREFETCH:REQUESTS openmp_test
>
> Could someone in the group please comment if expecting these counters to
> change, after disabling h/w prefetching in BIOS is correct?
>
> Regards,
> Ram
> Graduate student
>
> University of Houston
>
>
>
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------------------------------------------------------------------------------
Virtualization & Cloud Management Using Capacity Planning
Cloud computing makes use of virtualization - but cloud computing 
also focuses on allowing computing to be delivered as a service.
http://www.accelacomm.com/jaw/sfnl/114/51521223/
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