LU-12064 ptlrpc: set at_min=5 by default

Having at_min=0 as the default value can result in clients timing
out and/or being evicted too easily when there is a sudden spike
in server load.  Increase at_min to 5s by default.

For large clusters, at_min=15 is more reasonable, but distributing
a variable at_min value to clients will need more complex changes.

Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I3463cbc642458f6dd5977fe34478b135d1cd0219
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50609
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Aurelien Degremont <adegremont@nvidia.com>

diff --git a/lustre/obdclass/class_obd.c b/lustre/obdclass/class_obd.c
index 44a824a..bf33208 100644 (file)
--- a/lustre/obdclass/class_obd.c
+++ b/lustre/obdclass/class_obd.c
@@ -90,7 +90,7 @@ EXPORT_SYMBOL(ldlm_timeout_set);
 unsigned int bulk_timeout = 100; /* seconds */
 EXPORT_SYMBOL(bulk_timeout);
 /* Adaptive timeout defs here instead of ptlrpc module for /proc/sys/ access */
-unsigned int at_min = 0;
+unsigned int at_min = 5;
 EXPORT_SYMBOL(at_min);
 unsigned int at_max = 600;
 EXPORT_SYMBOL(at_max);