[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86: don't write_tsc() non-zero values on CPUs updating only the lower 32 bits
>>> On 14.04.11 at 18:48, Keir Fraser <keir.xen@xxxxxxxxx> wrote: > On 14/04/2011 17:28, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote: >> The only case not handled was if the TSC >> overflowed 64 bits during the process - I considered this case >> hypothetical only. >> >> The final write of tsc+4*delta was basically an attempt to restore >> the value that would have been there if we didn't fiddle with it. > > But the write is actually tsc + 4*(s32)(tmp-tsc), and tmp has 1U<<32 ORed > into it (because it was read after your second write to the TSC. Perhaps we > should just write back the full original tsc and call that good enough? Again, note the (s32) cast. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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