tree d4974c0ff9d7f40291515c5c0cf7e0d51abccb66
parent d3a9262e59f7fb83c6d44df3b2b1460ed57d3ea1
author Peter Zijlstra <a.p.zijlstra@chello.nl> 1238006377 +0100
committer Ingo Molnar <mingo@elte.hu> 1245329171 +0200

perf_counter: Add event overlow handling

Alternative method of mmap() data output handling that provides
better overflow management and a more reliable data stream.

Unlike the previous method, that didn't have any user->kernel
feedback and relied on userspace keeping up, this method relies on
userspace writing its last read position into the control page.

It will ensure new output doesn't overwrite not-yet read events,
new events for which there is no space left are lost and the
overflow counter is incremented, providing exact event loss
numbers.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>