Author: imp Date: Wed Sep 20 21:25:56 2017 New Revision: 323831 URL: https://svnweb.freebsd.org/changeset/base/323831
Log: cam iosched: Schedule cam_iosched_ticker() quanta times per second Previously callout_reset() was called with a "ticks" value that was off by one. As a result cam_iosched_ticker() was called a bit too frequently: On systems with hz=1000 a quanta value of 200 resulted in ~250 calls and a value of 100 in ~111 calls. For the "queue_depth" and "bandwidth" limiters the difference doesn't matter but the "iops" limiter depends on the scheduling to enforce the correct maximum. PR: 221956 Obtained from: ElectroBSD Submitted by: Fabian Keil Differential Revision: https://reviews.freebsd.org/D12350 Modified: head/sys/cam/cam_iosched.c Modified: head/sys/cam/cam_iosched.c ============================================================================== --- head/sys/cam/cam_iosched.c Wed Sep 20 21:22:20 2017 (r323830) +++ head/sys/cam/cam_iosched.c Wed Sep 20 21:25:56 2017 (r323831) @@ -533,7 +533,7 @@ cam_iosched_ticker(void *arg) sbintime_t now, delta; int pending; - callout_reset(&isc->ticker, hz / isc->quanta - 1, cam_iosched_ticker, isc); + callout_reset(&isc->ticker, hz / isc->quanta, cam_iosched_ticker, isc); now = sbinuptime(); delta = now - isc->last_time; @@ -798,7 +798,7 @@ cam_iosched_limiter_sysctl(SYSCTL_HANDLER_ARGS) return error; } /* Note: disk load averate requires ticker to be always running */ - callout_reset(&isc->ticker, hz / isc->quanta - 1, cam_iosched_ticker, isc); + callout_reset(&isc->ticker, hz / isc->quanta, cam_iosched_ticker, isc); isc->flags |= CAM_IOSCHED_FLAG_CALLOUT_ACTIVE; cam_periph_unlock(isc->periph); @@ -1055,7 +1055,7 @@ cam_iosched_init(struct cam_iosched_softc **iscp, stru callout_init_mtx(&(*iscp)->ticker, cam_periph_mtx(periph), 0); (*iscp)->periph = periph; cam_iosched_cl_init(&(*iscp)->cl, *iscp); - callout_reset(&(*iscp)->ticker, hz / (*iscp)->quanta - 1, cam_iosched_ticker, *iscp); + callout_reset(&(*iscp)->ticker, hz / (*iscp)->quanta, cam_iosched_ticker, *iscp); (*iscp)->flags |= CAM_IOSCHED_FLAG_CALLOUT_ACTIVE; } #endif _______________________________________________ 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"
