Author: imp
Date: Fri Sep 22 02:36:36 2017
New Revision: 323894
URL: https://svnweb.freebsd.org/changeset/base/323894
Log:
cam iosched: Bettar account IOPS for smoother performance
Prevent cam_iosched_iops_tick() from discarding 'unspent' ios unless
it's a new accounting interval.
Previously ios that weren't used between ticks were lost, as a result
the iops limiter could enforce a limit below the configured maximum.
Obtained from: ElectroBSD
Submitted by: Fabian Keil
PR: 221974
Modified:
head/sys/cam/cam_iosched.c
Modified: head/sys/cam/cam_iosched.c
==============================================================================
--- head/sys/cam/cam_iosched.c Fri Sep 22 02:36:32 2017 (r323893)
+++ head/sys/cam/cam_iosched.c Fri Sep 22 02:36:36 2017 (r323894)
@@ -423,19 +423,30 @@ cam_iosched_iops_init(struct iop_stats *ios)
static int
cam_iosched_iops_tick(struct iop_stats *ios)
{
+ int new_ios;
- if ((ios->softc->total_ticks % ios->softc->quanta) == 0)
- ios->l_value2 = 0;
-
- ios->l_value1 = (int)((ios->current * (uint64_t)ios->softc->this_frac)
>> 16);
/*
* Allow at least one IO per tick until all
* the IOs for this interval have been spent.
*/
- if (ios->l_value1 <= 0 && ios->l_value2 < ios->current) {
- ios->l_value1 = 1;
+ new_ios = (int)((ios->current * (uint64_t)ios->softc->this_frac) >> 16);
+ if (new_ios < 1 && ios->l_value2 < ios->current) {
+ new_ios = 1;
ios->l_value2++;
}
+
+ /*
+ * If this a new accounting interval, discard any "unspent" ios
+ * granted in the previous interval. Otherwise add the new ios to
+ * the previously granted ones that haven't been spent yet.
+ */
+ if ((ios->softc->total_ticks % ios->softc->quanta) == 0) {
+ ios->l_value1 = new_ios;
+ ios->l_value2 = 1;
+ } else {
+ ios->l_value1 += new_ios;
+ }
+
return 0;
}
_______________________________________________
svn-src-head@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
