[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Proposed XENMEM_claim_pages hypercall: Analysis of problem and alternate solutions
> From: Andres Lagar-Cavilla [mailto:andreslc@xxxxxxxxxxxxxx] > On Jan 2, 2013, at 4:43 PM, Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> > wrote: > > I reject the omnisicient toolstack model as unimplementable [1] > > and, without it, I think you either do need a separate allocation/list, > > with all the issues that entails, or you need the proposed > > XENMEM_claim_pages hypercall to resolve memory allocation races > > (i.e. vs domain creation). > > That pretty much ends the discussion. If you ask me below to reason within > the constraints your > rejection places, then that's artificial reasoning. Your rejection seems to > stem from philosophical > reasons, rather than technical limitations. Well, perhaps my statement is a bit heavy-handed, but I don't see how it ends the discussion... you simply need to prove my statement incorrect! ;-) To me, that would mean pointing out any existing implementation or even university research that successfully predicts or externally infers future memory demand for guests. (That's a good approximation of my definition of an omniscient toolstack.) But let's save that for another time or thread. > Look, your hyper call doesn't kill kittens, so that's about as far as I will > go in this discussion. Noted. I will look at adding kitten-killing functionality in the next revision. ;-) > My purpose here was to a) dispel misconceptions about sharing b) see if > something better comes out > from a discussion between all interested mm parties. I'm satisfied insofar a). At some time I hope to understand paging/sharing more completely and apologize, Andres, if I have cast aspersions about its/your implementation, I was simply trying to use it as another example of an in-hypervisor page allocation that is not directly under the control of the toolstack. I do understand and agree that IF the toolstack is capable of intelligently managing d->max_pages across all domains, then your model for handling CoW hits will be sufficient. So... again... peace? Dan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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