[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: Need help with fixing the Xen waitqueue feature
On Tue, Nov 08, Andres Lagar-Cavilla wrote: > Tbh, for paging to be effective, we need to be prepared to yield on every > p2m lookup. Yes, if a gfn is missing the vcpu should go to sleep rather than returning -ENOENT to the caller. Only the query part of gfn_to_mfn should return the p2m paging types. > Let's compare paging to PoD. They're essentially the same thing: pages > disappear, and get allocated on the fly when you need them. PoD is a > highly optimized in-hypervisor optimization that does not need a > user-space helper -- but the pager could do PoD easily and remove all that > p2m-pod.c code from the hypervisor. Perhaps PoD and paging could be merged, I havent had time to study the PoD code. > PoD only introduces extraneous side-effects when there is a complete > absence of memory to allocate pages. The same cannot be said of paging, to > put it mildly. It returns EINVAL all over the place. Right now, qemu can > be crashed in a blink by paging out the right gfn. I have seen qemu crashes when using emulated storage, but havent debugged them yet. I suspect they were caused by a race between nominate and evict. Olaf _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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