Messages in this thread | | | Subject | Re: [PATCH 1/2] perf: Add persistent event facilities | From | Peter Zijlstra <> | Date | Fri, 18 May 2012 15:37:47 +0200 |
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On Fri, 2012-05-18 at 14:55 +0200, Borislav Petkov wrote: > It is an interesting question how we handle that RO/RW thing?
RO buffers overwrite, RW buffers loose events.
We could allow both for persistent under the constraints:
VM_SHARED - must imply !VM_WRITE since multiple people writing to the control page will get 'interesting' very fast.
!VM_SHARED - must fail mmap() of the debugfs file if there's already an existing user.
Note that even RW buffers only allows writes to the control page, a write to the actual data itself will generate a fault.
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