Hi Nilay, To solve the first problem, can you use the Maybe_Stale AccessPermission identify the last possible valid copy of the data block? It seems like if a functional read can't find valid data anywhere else, then you are guaranteed that the Maybe_Stale block at the directory is valid.
With this change, we should be able to get rid of the physmem backing store in Ruby, correct? Have you tried that sort of test with this patch? Especially an application under SE mode that uses a lot of system calls? 45 files modified...have I told you how much I dislike this patch. :) Brad > -----Original Message----- > From: Nilay Vaish [mailto:[email protected]] > Sent: Wednesday, October 03, 2012 10:02 PM > To: Andreas Hansson; Default; Beckmann, Brad > Subject: Re: Review Request: ruby: augment network to support functional > accesses > > Some comments on the patch -- > > * The way the code has been written, functional writes will always succeed, > but functional reads can still fail. This can be illustrated with an example. > Consider the situation when the directory has the actual data, but it believes > that the ownership of the data is with some other controller. This other > controller has relinquished the ownership with out modifying the data. The > info about relinquishment is in the network currently. The read would fail > since we need to know both pieces of info to figure out that the directory > has the data. We would need greater cooperation from protocols for reads > to succeed all the time. > > * I have done some testing with the memtest (1 to 8 cores, 160000 loads). > But no testing has been done when dma requests/replies are part of the > system. > > * No support for garnet as of now. > > * Coherence protocols MI, MOESI CMP token have been changed slightly. > These changes have been vetted only with the memtest. > > -- > Nilay _______________________________________________ gem5-dev mailing list [email protected] http://m5sim.org/mailman/listinfo/gem5-dev
