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Date:      Wed, 16 Oct 2013 09:12:41 +0000 (UTC)
From:      Alexander Motin <mav@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r256603 - in head/sys: geom kern sys
Message-ID:  <201310160912.r9G9CfZd098426@svn.freebsd.org>
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Author: mav
Date: Wed Oct 16 09:12:40 2013
New Revision: 256603
URL: http://svnweb.freebsd.org/changeset/base/256603

Log:
  MFprojects/camlock r254905:
  Introduce new function devstat_end_transaction_bio_bt(), adding new argument
  to specify present time.  Use this function to move binuptime() out of lock,
  substantially reducing lock congestion when slow timecounter is used.

Modified:
  head/sys/geom/geom_disk.c
  head/sys/geom/geom_io.c
  head/sys/kern/subr_devstat.c
  head/sys/sys/devicestat.h

Modified: head/sys/geom/geom_disk.c
==============================================================================
--- head/sys/geom/geom_disk.c	Wed Oct 16 09:05:49 2013	(r256602)
+++ head/sys/geom/geom_disk.c	Wed Oct 16 09:12:40 2013	(r256603)
@@ -229,6 +229,7 @@ g_disk_setstate(struct bio *bp, struct g
 static void
 g_disk_done(struct bio *bp)
 {
+	struct bintime now;
 	struct bio *bp2;
 	struct g_disk_softc *sc;
 
@@ -237,12 +238,13 @@ g_disk_done(struct bio *bp)
 	bp2 = bp->bio_parent;
 	sc = bp2->bio_to->private;
 	bp->bio_completed = bp->bio_length - bp->bio_resid;
+	binuptime(&now);
 	mtx_lock(&sc->done_mtx);
 	if (bp2->bio_error == 0)
 		bp2->bio_error = bp->bio_error;
 	bp2->bio_completed += bp->bio_completed;
 	if ((bp->bio_cmd & (BIO_READ|BIO_WRITE|BIO_DELETE)) != 0)
-		devstat_end_transaction_bio(sc->dp->d_devstat, bp);
+		devstat_end_transaction_bio_bt(sc->dp->d_devstat, bp, &now);
 	g_destroy_bio(bp);
 	bp2->bio_inbed++;
 	if (bp2->bio_children == bp2->bio_inbed) {

Modified: head/sys/geom/geom_io.c
==============================================================================
--- head/sys/geom/geom_io.c	Wed Oct 16 09:05:49 2013	(r256602)
+++ head/sys/geom/geom_io.c	Wed Oct 16 09:12:40 2013	(r256603)
@@ -511,6 +511,7 @@ g_io_request(struct bio *bp, struct g_co
 void
 g_io_deliver(struct bio *bp, int error)
 {
+	struct bintime now;
 	struct g_consumer *cp;
 	struct g_provider *pp;
 	int first;
@@ -564,11 +565,13 @@ g_io_deliver(struct bio *bp, int error)
 	 * can not update one instance of the statistics from more
 	 * than one thread at a time, so grab the lock first.
 	 */
+	if (g_collectstats)
+		binuptime(&now);
 	g_bioq_lock(&g_bio_run_up);
 	if (g_collectstats & 1)
-		devstat_end_transaction_bio(pp->stat, bp);
+		devstat_end_transaction_bio_bt(pp->stat, bp, &now);
 	if (g_collectstats & 2)
-		devstat_end_transaction_bio(cp->stat, bp);
+		devstat_end_transaction_bio_bt(cp->stat, bp, &now);
 
 	cp->nend++;
 	pp->nend++;

Modified: head/sys/kern/subr_devstat.c
==============================================================================
--- head/sys/kern/subr_devstat.c	Wed Oct 16 09:05:49 2013	(r256602)
+++ head/sys/kern/subr_devstat.c	Wed Oct 16 09:12:40 2013	(r256603)
@@ -374,6 +374,14 @@ devstat_end_transaction(struct devstat *
 void
 devstat_end_transaction_bio(struct devstat *ds, struct bio *bp)
 {
+
+	devstat_end_transaction_bio_bt(ds, bp, NULL);
+}
+
+void
+devstat_end_transaction_bio_bt(struct devstat *ds, struct bio *bp,
+    struct bintime *now)
+{
 	devstat_trans_flags flg;
 
 	/* sanity check */
@@ -390,7 +398,7 @@ devstat_end_transaction_bio(struct devst
 		flg = DEVSTAT_NO_DATA;
 
 	devstat_end_transaction(ds, bp->bio_bcount - bp->bio_resid,
-				DEVSTAT_TAG_SIMPLE, flg, NULL, &bp->bio_t0);
+				DEVSTAT_TAG_SIMPLE, flg, now, &bp->bio_t0);
 	DTRACE_DEVSTAT_BIO_DONE();
 }
 

Modified: head/sys/sys/devicestat.h
==============================================================================
--- head/sys/sys/devicestat.h	Wed Oct 16 09:05:49 2013	(r256602)
+++ head/sys/sys/devicestat.h	Wed Oct 16 09:12:40 2013	(r256603)
@@ -199,6 +199,8 @@ void devstat_end_transaction(struct devs
 			     devstat_trans_flags flags,
 			     struct bintime *now, struct bintime *then);
 void devstat_end_transaction_bio(struct devstat *ds, struct bio *bp);
+void devstat_end_transaction_bio_bt(struct devstat *ds, struct bio *bp,
+			     struct bintime *now);
 #endif
 
 #endif /* _DEVICESTAT_H */

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