Date: | Fri, 18 Dec 2009 23:44:18 -0800 (PST) |
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From: | Muhammad abid Mughal <mabidm_pieas@xxxxxxxxx> |
Subject: | Re: [Gems-users] Does gems (ruby) model the DMA operations now? |
Hi, Is gems aware this? yes If you are using Simics and Ruby then for every memory operation(ie ld/st/atomic/ifetch/prefetch/dma/io, etc) simics calls this function SimicsDriver::makeRequest() and this function filters out all unsupported operations(ie i/o , DMA,cache flush, prefetch) via SimicsDriver::isUnhandledTransaction(). so this way DMA/ io operations are not passed to Ruby and not cached in any caches. Do you have any idea about how to know where are the I/O blocks? you need to make some changes to this function SimicsDriver::isUnhandledTransaction(). whenever memory is accessed by DMA or
I/O device this IS_DEV_MEM_OP(mem_trans->s.ini_type) returns true and you can use 'mem_trans' arg to do some profiling Hope it helps Regards, Muhammad abid
From: Sitos Lin <sitos.lin@xxxxxxxxx> To: Gems Users <gems-users@xxxxxxxxxxx> Sent: Saturday, December 19, 2009 14:52:44 Subject: Re: [Gems-users] Does gems (ruby) model the DMA operations now? Hello: You said that " DMA accesses I/O blocks and Ultrasparc processor does not allow caching of I/O blocks". Is gems aware this? If the I/O blocks are uncacheable, maybe I can gather the memory accesses correspondent to DMA operations by monitoring the memory accesses belong to I/O blocks by knowing the memory range of I/O blocks. Do you have any idea about how to know where are the I/O blocks? Thank you. Best regards, Sitos 2009/12/18 Muhammad abid Mughal <mabidm_pieas@xxxxxxxxx>: > hi > I do know that Ruby does not support DMA requests even in gems-2.1. It just > filters them out via SimicsDriver::isunhandledtransaction(), so its not > possible for DMA requests to invalidate the corresponding cache blocks in > L1/L2 caches[i am wondering that DMA accesses I/O blocks and Ultrasparc > processor does not allow caching of i/o blocks, so no question of > invalidating corresponding L1$/L2$ blocks.am i right?] > Regards, > Muhammad abid > ________________________________ > From: Sitos Lin <sitos.lin@xxxxxxxxx> > To: gems-users@xxxxxxxxxxx > Sent: Friday, December 18, 2009 11:24:41 > Subject: [Gems-users] Does gems (ruby) model the DMA operations now? > > Hello all: > I want to use gems (ruby) to capture the memory access trace. > However, I am wondering if gems models the DMA operations. In the > paper, it says "Also, Ruby does not model the memory system traffic > due to direct memory access (DMA) operations or memory-mapped I/O > loads and stores." However, gems is now version 2.1. Does gems model > the DMA operations now? > Besides that, if the memory system traffic of DMA operations are not > modeled, I want to know if DMA operations invalidate the correspondent > cache blocks in L1/L2 caches. Since the values of memory have been > changed by DMA (read) operations, the cache blocks should be > invalidated and the following cache accesses to these lines should be > miss. I have tried to test gems by two simple program. However, the > results are not consistent to my knowledge. The program with > additional DMAs causes less cache misses than another one without DMA > operation. > If gems can not model the features mentioned above, I will try other > approaches. > Best regards, > Sitos > _______________________________________________ > Gems-users mailing list > Gems-users@xxxxxxxxxxx > https://lists.cs.wisc.edu/mailman/listinfo/gems-users > Use Google to search the GEMS Users mailing list by adding > "site:https://lists.cs.wisc.edu/archive/gems-users/" to your search. > > > ________________________________ > New Email addresses available on Yahoo! > Get the Email name you've always wanted on the new @ymail and @rocketmail. > Hurry before someone else does! > _______________________________________________ > Gems-users mailing list > Gems-users@xxxxxxxxxxx > https://lists.cs.wisc.edu/mailman/listinfo/gems-users > Use Google to search the GEMS Users mailing list by adding > "site:https://lists.cs.wisc.edu/archive/gems-users/" to your search. > > > _______________________________________________ Gems-users mailing list Gems-users@xxxxxxxxxxx https://lists.cs.wisc.edu/mailman/listinfo/gems-users Use Google to search the GEMS Users mailing list by adding "site:https://lists.cs.wisc.edu/archive/gems-users/" to your search. New Email names for you! Get the Email name you've always wanted on the new @ymail and @rocketmail. Hurry before someone else does! |
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