Re: [Gems-users] prefetch in opal

[Jerry Lin <cosjerry@xxxxxxxxx>]

Hi,

I have some more questions.

How does the software prefetch implemented in opal?

It seems that it didn't modify the compiler, then how to insert software prefetch instructions into an application?

And what's the software prefetch policy? How to decide what line to prefetch into cache?

When I using MOSI_SMP_bcast protocol to run simulation, there are both non-zero prefetch count in L1D_cache and L2_cache.

Is there any difference in prefetching policy? 

Thanks for your reply.

Regards.

 

2010/6/29 Muhammad abid Mughal <mabidm_pieas@xxxxxxxxx>

hi,

    Opal implements both hardware(ie next line prefetcher for instruction cache) and software prefetch(prefetch_inst_t).But in ruby you can not differentiate b/w theses two because both prefetches use "PrefetchBit_Yes" when issued to ruby [ see OpalInterface::makePrefetch(....).]

But its easy to differentiate b/w these two.

Regards,

Muhammad abid

---

From: Jerry Lin <cosjerry@xxxxxxxxx>
To: Gems Users <gems-users@xxxxxxxxxxx>
Sent: Tuesday, June 29, 2010 19:31:40
Subject: [Gems-users] prefetch in opal

Hello all,
I'm wondering about what kind of prefetching that opal implemented.

I saw Next Line prefetch in opal/system/rubycache.C.

But in ruby's dump file, the prefetch count seems to be the software prefetch.

Is the prefetching policy implemented in opal a HW prefetch or SW prefetch?

Any advice would be appreciated. 

 
Thanks for helping.

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