Messages in this thread Patch in this message | | | From | James Hogan <> | Subject | [PATCH 2/9] metag: perf: fix wrap handling in delta calculation | Date | Fri, 15 Mar 2013 13:43:41 +0000 |
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When calculating the delta, mask with MAX_PERIOD (24 bits) to handle wrapping, which particularly happens with periodic sampling since the value is intentionally set so that it will overflow soon.
Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> --- arch/metag/kernel/perf/perf_event.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/metag/kernel/perf/perf_event.c b/arch/metag/kernel/perf/perf_event.c index f38bf6d..8096db2 100644 --- a/arch/metag/kernel/perf/perf_event.c +++ b/arch/metag/kernel/perf/perf_event.c @@ -211,7 +211,7 @@ again: /* * Calculate the delta and add it to the counter. */ - delta = new_raw_count - prev_raw_count; + delta = (new_raw_count - prev_raw_count) & MAX_PERIOD; local64_add(delta, &event->count); } -- 1.8.1.2
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