From: Alexander Zarochentsev Date: Sun, 18 Sep 2016 20:37:04 +0000 (-0400) Subject: staging: lustre: obdclass: optimize busy loop wait X-Git-Tag: v4.9.8~1233^2~498 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2e1ff4515adf956a47d98b2a711e2775f2406d44;p=platform%2Fkernel%2Flinux-rpi3.git staging: lustre: obdclass: optimize busy loop wait 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 Signed-off-by: Greg Kroah-Hartman --- 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) {