Hi Erik,
You can use the debug-flag CacheRepl and see what is getting replaced and when. Ali On 13.03.2013 11:09, Erik Tomusk wrote: > Hi Ali. > > I don't think just a direct mapping from virtual to physical addresses can explain this behavior. In the benchmark, I have one, contiguous chunk of data that I read repeatedly. In the case where I see the strange behavior, the direct-mapped data cache is 2x bigger than the data. Even with worst-case mapping, this should produce very few collisions. > > Is there a way to see what's going on under the hood in gem5 that might be causing the cache to miss? I've ruled out the compiler doing anything strange. > > Thanks, > Erik > > On 12/03/13 18:26, Ali Saidi wrote: > >> Hi Erik, >> >> It doesn't, but memory allocation is pretty dump in SE mode. VA -> PA, so it's certainly possible you're getting into a case where lots of things conflict. >> >> Ali >> >> On 12.03.2013 16:27, Erik Tomusk wrote: >> >>> Hello All, >>> >>> Does the classic memory model do any sort of address hashing or other >>> similar magic when storing data in the L1D cache? >>> >>> I've been running a very simple microbenchmark with varying sizes of the >>> L1D cache and data set (in SE mode). For a very small number of >>> combinations of data set and cache size, miss rate goes through the roof >>> (>50x what might be expected based on other simulations). This is >>> consistent with e.g. a collision in a hash function for mapping logical >>> addresses to physical ones. >>> >>> I thought I'd ask if this is expected behavior before I go digging >>> through the code. >>> >>> Thanks, >>> Erik >> >> _______________________________________________ >> gem5-users mailing list >> gem5-users@gem5.org >> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users [1] > > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > _______________________________________________ > gem5-users mailing list > gem5-users@gem5.org > http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users [1] Links: ------ [1] http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users
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