From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755362Ab3CONr1 (ORCPT ); Fri, 15 Mar 2013 09:47:27 -0400 Received: from multi.imgtec.com ([194.200.65.239]:34593 "EHLO multi.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754482Ab3CONoe (ORCPT ); Fri, 15 Mar 2013 09:44:34 -0400 From: James Hogan To: CC: James Hogan , Peter Zijlstra , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo Subject: [PATCH 2/9] metag: perf: fix wrap handling in delta calculation Date: Fri, 15 Mar 2013 13:43:41 +0000 Message-ID: <1363355028-23278-3-git-send-email-james.hogan@imgtec.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1363355028-23278-1-git-send-email-james.hogan@imgtec.com> References: <1363355028-23278-1-git-send-email-james.hogan@imgtec.com> MIME-Version: 1.0 Content-Type: text/plain X-SEF-Processed: 7_3_0_01181__2013_03_15_13_44_30 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo --- 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