Date: Tue, 8 Dec 2009 23:34:34 +0000 (UTC) From: Alexander Motin <mav@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-7@freebsd.org Subject: svn commit: r200286 - stable/7/sys/geom/mirror Message-ID: <200912082334.nB8NYYhY005211@svn.freebsd.org>
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Author: mav Date: Tue Dec 8 23:34:34 2009 New Revision: 200286 URL: http://svn.freebsd.org/changeset/base/200286 Log: MFC r200086: Change 'load' balancing mode algorithm: - Instead of measuring last request execution time for each drive and choosing one with smallest time, use averaged number of requests, running on each drive. This information is more accurate and timely. It allows to distribute load between drives in more even and predictable way. - For each drive track offset of the last submitted request. If new request offset matches previous one or close for some drive, prefer that drive. It allows to significantly speedup simultaneous sequential reads. PR: kern/113885 Modified: stable/7/sys/geom/mirror/g_mirror.c stable/7/sys/geom/mirror/g_mirror.h Directory Properties: stable/7/sys/ (props changed) stable/7/sys/contrib/pf/ (props changed) Modified: stable/7/sys/geom/mirror/g_mirror.c ============================================================================== --- stable/7/sys/geom/mirror/g_mirror.c Tue Dec 8 23:23:45 2009 (r200285) +++ stable/7/sys/geom/mirror/g_mirror.c Tue Dec 8 23:34:34 2009 (r200286) @@ -451,9 +451,6 @@ g_mirror_init_disk(struct g_mirror_softc disk->d_id = md->md_did; disk->d_state = G_MIRROR_DISK_STATE_NONE; disk->d_priority = md->md_priority; - disk->d_delay.sec = 0; - disk->d_delay.frac = 0; - binuptime(&disk->d_last_used); disk->d_flags = md->md_dflags; if (md->md_provider[0] != '\0') disk->d_flags |= G_MIRROR_DISK_FLAG_HARDCODED; @@ -863,16 +860,6 @@ bintime_cmp(struct bintime *bt1, struct } static void -g_mirror_update_delay(struct g_mirror_disk *disk, struct bio *bp) -{ - - if (disk->d_softc->sc_balance != G_MIRROR_BALANCE_LOAD) - return; - binuptime(&disk->d_delay); - bintime_sub(&disk->d_delay, &bp->bio_t0); -} - -static void g_mirror_done(struct bio *bp) { struct g_mirror_softc *sc; @@ -904,8 +891,6 @@ g_mirror_regular_request(struct bio *bp) g_topology_lock(); g_mirror_kill_consumer(sc, bp->bio_from); g_topology_unlock(); - } else { - g_mirror_update_delay(disk, bp); } pbp->bio_inbed++; @@ -1465,30 +1450,35 @@ g_mirror_request_round_robin(struct g_mi g_io_request(cbp, cp); } +#define TRACK_SIZE (1 * 1024 * 1024) +#define LOAD_SCALE 256 +#define ABS(x) (((x) >= 0) ? (x) : (-(x))) + static void g_mirror_request_load(struct g_mirror_softc *sc, struct bio *bp) { struct g_mirror_disk *disk, *dp; struct g_consumer *cp; struct bio *cbp; - struct bintime curtime; + int prio, best; - binuptime(&curtime); - /* - * Find a disk which the smallest load. - */ + /* Find a disk with the smallest load. */ disk = NULL; + best = INT_MAX; LIST_FOREACH(dp, &sc->sc_disks, d_next) { if (dp->d_state != G_MIRROR_DISK_STATE_ACTIVE) continue; - /* If disk wasn't used for more than 2 sec, use it. */ - if (curtime.sec - dp->d_last_used.sec >= 2) { - disk = dp; - break; - } - if (disk == NULL || - bintime_cmp(&dp->d_delay, &disk->d_delay) < 0) { + prio = dp->load; + /* If disk head is precisely in position - highly prefer it. */ + if (dp->d_last_offset == bp->bio_offset) + prio -= 2 * LOAD_SCALE; + else + /* If disk head is close to position - prefer it. */ + if (ABS(dp->d_last_offset - bp->bio_offset) < TRACK_SIZE) + prio -= 1 * LOAD_SCALE; + if (prio <= best) { disk = dp; + best = prio; } } KASSERT(disk != NULL, ("NULL disk for %s.", sc->sc_name)); @@ -1505,12 +1495,18 @@ g_mirror_request_load(struct g_mirror_so cp = disk->d_consumer; cbp->bio_done = g_mirror_done; cbp->bio_to = cp->provider; - binuptime(&disk->d_last_used); G_MIRROR_LOGREQ(3, cbp, "Sending request."); KASSERT(cp->acr >= 1 && cp->acw >= 1 && cp->ace >= 1, ("Consumer %s not opened (r%dw%de%d).", cp->provider->name, cp->acr, cp->acw, cp->ace)); cp->index++; + /* Remember last head position */ + disk->d_last_offset = bp->bio_offset + bp->bio_length; + /* Update loads. */ + LIST_FOREACH(dp, &sc->sc_disks, d_next) { + dp->load = (dp->d_consumer->index * LOAD_SCALE + + dp->load * 7) / 8; + } g_io_request(cbp, cp); } Modified: stable/7/sys/geom/mirror/g_mirror.h ============================================================================== --- stable/7/sys/geom/mirror/g_mirror.h Tue Dec 8 23:23:45 2009 (r200285) +++ stable/7/sys/geom/mirror/g_mirror.h Tue Dec 8 23:34:34 2009 (r200286) @@ -133,8 +133,8 @@ struct g_mirror_disk { struct g_mirror_softc *d_softc; /* Back-pointer to softc. */ int d_state; /* Disk state. */ u_int d_priority; /* Disk priority. */ - struct bintime d_delay; /* Disk delay. */ - struct bintime d_last_used; /* When disk was last used. */ + u_int load; /* Averaged queue length */ + off_t d_last_offset; /* Last read offset */ uint64_t d_flags; /* Additional flags. */ u_int d_genid; /* Disk's generation ID. */ struct g_mirror_disk_sync d_sync;/* Sync information. */
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