From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936405AbcIRUkN (ORCPT ); Sun, 18 Sep 2016 16:40:13 -0400 Received: from smtp2.ccs.ornl.gov ([160.91.203.11]:58126 "EHLO smtp2.ccs.ornl.gov" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964934AbcIRUjl (ORCPT ); Sun, 18 Sep 2016 16:39:41 -0400 From: James Simmons To: Greg Kroah-Hartman , devel@driverdev.osuosl.org, Andreas Dilger , Oleg Drokin Cc: Linux Kernel Mailing List , Lustre Development List , Alexander Zarochentsev , James Simmons Subject: [PATCH 005/124] staging: lustre: obdclass: optimize busy loop wait Date: Sun, 18 Sep 2016 16:37:04 -0400 Message-Id: <1474231143-4061-6-git-send-email-jsimmons@infradead.org> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1474231143-4061-1-git-send-email-jsimmons@infradead.org> References: <1474231143-4061-1-git-send-email-jsimmons@infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexander Zarochentsev two optimizations in the busy loop wait in class_cleanup(): (1) remove unnecessary spinlocks protecting obd_conn_inprogress access (2) replace cond_resched by more suitable yield to unconditionally yield the CPU if the condition check fails. Signed-off-by: Alexander Zarochentsev Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5397 Xyratex-bug-id: MRP-1991 Reviewed-on: http://review.whamcloud.com/11198 Reviewed-by: Andreas Dilger Reviewed-by: Dmitry Eremin Reviewed-by: Oleg Drokin Signed-off-by: James Simmons --- .../staging/lustre/lustre/obdclass/obd_config.c | 13 ++++--------- 1 files changed, 4 insertions(+), 9 deletions(-) diff --git a/drivers/staging/lustre/lustre/obdclass/obd_config.c b/drivers/staging/lustre/lustre/obdclass/obd_config.c index 036f396..fddfc9c 100644 --- a/drivers/staging/lustre/lustre/obdclass/obd_config.c +++ b/drivers/staging/lustre/lustre/obdclass/obd_config.c @@ -414,17 +414,12 @@ static int class_cleanup(struct obd_device *obd, struct lustre_cfg *lcfg) } /* Leave this on forever */ obd->obd_stopping = 1; - - /* wait for already-arrived-connections to finish. */ - while (obd->obd_conn_inprogress > 0) { - spin_unlock(&obd->obd_dev_lock); - - cond_resched(); - - spin_lock(&obd->obd_dev_lock); - } spin_unlock(&obd->obd_dev_lock); + while (obd->obd_conn_inprogress > 0) + yield(); + smp_rmb(); + if (lcfg->lcfg_bufcount >= 2 && LUSTRE_CFG_BUFLEN(lcfg, 1) > 0) { for (flag = lustre_cfg_string(lcfg, 1); *flag != 0; flag++) switch (*flag) { -- 1.7.1