Messages in this thread | | | Date | Fri, 25 Jul 2014 18:40:41 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH v3 6/9] perf, x86: handle multiple records in PEBS buffer |
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> Suppose two pebs events, one has exclude_kernel set. It overflows, > before entering the kernel, the other event generates PEBS records from > inside the kernel with both events marked in the overflow field. > > And only once we leave the kernel can the exclude_kernel event tick > again and trigger the assist, finalyl clearing the bit. > > If you were to report the records to both events, one would get a lot of > kernel info he was not entitled to.
Ok that case can be filtered in software. Shouldn't be too difficult. Perhaps just using ip
if (event->attr.exclude_kernel && pebs->ip >= __PAGE_OFFSET) skip; if (event->attr.exclude_user && pebs->ip < __PAGE_OFFSET) skip;
This would also help with the existing skid.
Any other concerns?
-Andi
-- ak@linux.intel.com -- Speaking for myself only.
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