From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752823AbdA2Aa6 (ORCPT ); Sat, 28 Jan 2017 19:30:58 -0500 Received: from [160.91.203.10] ([160.91.203.10]:49074 "EHLO smtp1.ccs.ornl.gov" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752920AbdA2Aai (ORCPT ); Sat, 28 Jan 2017 19:30:38 -0500 From: James Simmons To: Greg Kroah-Hartman , devel@driverdev.osuosl.org, Andreas Dilger , Oleg Drokin Cc: Linux Kernel Mailing List , Lustre Development List , James Simmons , James Simmons Subject: [PATCH 58/60] staging: lustre: osc: avoid 64 divide in osc_cache_too_much Date: Sat, 28 Jan 2017 19:05:26 -0500 Message-Id: <1485648328-2141-59-git-send-email-jsimmons@infradead.org> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1485648328-2141-1-git-send-email-jsimmons@infradead.org> References: <1485648328-2141-1-git-send-email-jsimmons@infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The use of 64 bit time introduces an expensive 64 bit division operation. Since the time lapse being calculated in osc_cache_too_much will never be more than seventy years we can cast the time lapse to an long and perform a normal 32 bit divison operation instead. Signed-off-by: James Simmons Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8835 Reviewed-on: https://review.whamcloud.com/23814 Reviewed-by: Andreas Dilger Reviewed-by: Dmitry Eremin Signed-off-by: James Simmons --- drivers/staging/lustre/lustre/osc/osc_page.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/staging/lustre/lustre/osc/osc_page.c b/drivers/staging/lustre/lustre/osc/osc_page.c index 0461408..ab9d0d7 100644 --- a/drivers/staging/lustre/lustre/osc/osc_page.c +++ b/drivers/staging/lustre/lustre/osc/osc_page.c @@ -370,12 +370,17 @@ static int osc_cache_too_much(struct client_obd *cli) return lru_shrink_min(cli); } else { time64_t duration = ktime_get_real_seconds(); + long timediff; /* knock out pages by duration of no IO activity */ duration -= cli->cl_lru_last_used; - duration >>= 6; /* approximately 1 minute */ - if (duration > 0 && - pages >= div64_s64((s64)budget, duration)) + /* + * The difference shouldn't be more than 70 years + * so we can safely case to a long. Round to + * approximately 1 minute. + */ + timediff = (long)(duration >> 6); + if (timediff > 0 && pages >= budget / timediff) return lru_shrink_min(cli); } return 0; -- 1.8.3.1