From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751036AbdBTX7S (ORCPT ); Mon, 20 Feb 2017 18:59:18 -0500 Received: from mail-pg0-f53.google.com ([74.125.83.53]:33588 "EHLO mail-pg0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750826AbdBTX7R (ORCPT ); Mon, 20 Feb 2017 18:59:17 -0500 From: David Riley To: Thomas Gleixner , John Stultz Cc: Russell King , LKML , David Riley Subject: [PATCH] kernel: time: Modify test_udelay to allow for 1% tolerance. Date: Mon, 20 Feb 2017 15:59:08 -0800 Message-Id: <20170220235908.17541-1-davidriley@chromium.org> X-Mailer: git-send-email 2.11.0.483.g087da7b7c-goog Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org test_udelay had a tolerance of udelay() being up to 0.5% fast but that tolerance is insufficient for some platforms. For ARM, the error is around 0.7% so increase the test to allow for up to 1% which was previously described as being acceptable for udelay(). See the following thread for more details: http://lists.openwall.net/linux-kernel/2011/01/12/372 Cc: John Stultz Cc: Thomas Gleixner Cc: Russell King Signed-off-by: David Riley --- kernel/time/test_udelay.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/time/test_udelay.c b/kernel/time/test_udelay.c index b0928ab..5212925 100644 --- a/kernel/time/test_udelay.c +++ b/kernel/time/test_udelay.c @@ -39,8 +39,8 @@ static int udelay_test_single(struct seq_file *s, int usecs, uint32_t iters) uint64_t sum = 0; uint64_t avg; int i; - /* Allow udelay to be up to 0.5% fast */ - int allowed_error_ns = usecs * 5; + /* Allow udelay to be up to 1% fast */ + int allowed_error_ns = usecs * 10; for (i = 0; i < iters; ++i) { s64 kt1, kt2; -- 2.2.1