[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Need help with fixing the Xen waitqueue feature
On 08/11/2011 21:20, "Olaf Hering" <olaf@xxxxxxxxx> wrote: > Another thing is that sometimes the host suddenly reboots without any > message. I think the reason for this is that a vcpu whose stack was put > aside and that was later resumed may find itself on another physical > cpu. And if that happens, wouldnt that invalidate some of the local > variables back in the callchain? If some of them point to the old > physical cpu, how could this be fixed? Perhaps a few "volatiles" are > needed in some places. >From how many call sites can we end up on a wait queue? I know we were going to end up with a small and explicit number (e.g., in __hvm_copy()) but does this patch make it a more generally-used mechanism? There will unavoidably be many constraints on callers who want to be able to yield the cpu. We can add Linux-style get_cpu/put_cpu abstractions to catch some of them. Actually I don't think it's *that* common that hypercall contexts cache things like per-cpu pointers. But every caller will need auditing, I expect. A sudden reboot is very extreme. No message even on a serial line? That most commonly indicates bad page tables. Most other bugs you'd at least get a double fault message. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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