Messages in this thread | | | Subject | Re: [RFC][PATCH 0/6] perf: x86 RDPMC and RDTSC support | From | Peter Zijlstra <> | Date | Wed, 21 Dec 2011 23:32:59 +0100 |
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On Wed, 2011-12-21 at 17:19 -0500, Vince Weaver wrote: > > Speaking of bit 48, does your implementation do anything useful about > the 32/40/48 bit limitation that some processors have with rdpmc? > Or is the answer that if you might get overflow, then you have to use slow > syscall-based read?
Yeah, we program an overflow interrupt around there (47 bits iirc) and consume the total into the u64 count value and update the mmap control page's offset.
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