From: Alexander Zarochentsev <alexander_zarochentsev@xxxxxxxxxxx>
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 <alexander_zarochentsev@xxxxxxxxxxx>
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 <andreas.dilger@xxxxxxxxx>
Reviewed-by: Dmitry Eremin <dmitry.eremin@xxxxxxxxx>
Reviewed-by: Oleg Drokin <oleg.drokin@xxxxxxxxx>
Signed-off-by: James Simmons <jsimmons@xxxxxxxxxxxxx>
---
.../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
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