Messages in this thread | | | Date | Tue, 17 Aug 2010 14:53:31 +1000 | From | Paul Mackerras <> | Subject | Re: [RFC PATCH 5/6 v4] perf: Fix race in callchains |
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On Tue, Aug 17, 2010 at 03:34:06AM +0200, Frederic Weisbecker wrote:
> Now that software events don't have interrupt disabled anymore in > the event path, callchains can nest on any context. So seperating > nmi and others contexts in two buffers has become racy. > > Fix this by providing one buffer per nesting level. Given the size > of the callchain entries (2040 bytes * 4), we now need to allocate > them dynamically. > > v2: Fixed put_callchain_entry call after recursion. > Fix the type of the recursion, it must be an array. > > v3: Use a manual pr cpu allocation (temporary solution until NMIs > can safely access vmalloc'ed memory).
It would be nice to make these allocations node-local.
Also, I see that we're allocating 4 buffers per cpu on powerpc when we strictly only need 3, but I don't suppose that really matters.
Paul.
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