Hi Nilay, It did not do anything sensible. The MemTest fundamentally only tests false sharing since it has no notion of a memory consistency model. Thus, the “non DMA” transactions access a specific byte in the cache line.
The DMA transactions were multi-byte transactions, that had no tests associated. In essence all it did was to inject some larger packets and ignoring what happened to them. I don’t see the point. We have a proper MemChecker in gem5, and I have created another memchecker.py test that uses TrafficGen and MemChecker instances to test actual sharing. This adds significant value (compared to the rather pointless “DMA” part of MemTest). I simply do not see why the “DMA” part was every useful. Andreas On 03/02/2015 19:05, "Nilay Vaish" <ni...@cs.wisc.edu> wrote: >On Sun, 1 Feb 2015, Andreas Hansson wrote: > >> Hi Nilay, >> >> I think the “DMA” bit of this tester was broken and rather pointless. In >> essence the MemTest is only fit for testing false sharing, and that is >> what it now does. I do not quite understand what a DMA has to do with >>any >> of that. >> >> Separately we will now have a tester that actually tests actual sharing, >> and does so using larger chunks of data being touched (in units of whole >> cache lines). I think this is a much more sensible strategy. >> >> What is the value of the “DMA” bit in MemTest and why does it make sense >> to keep it there? >> > > >DMA controller is also a party in the memory system. If a ruby protocol >provides a DMA controller, then it also needs to be tested for >correctness. I think we had it there so that one can choose whether or >not to test the DMA controller. > >-- >Nilay -- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. ARM Limited, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ, Registered in England & Wales, Company No: 2557590 ARM Holdings plc, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ, Registered in England & Wales, Company No: 2548782 _______________________________________________ gem5-dev mailing list gem5-dev@gem5.org http://m5sim.org/mailman/listinfo/gem5-dev
