Date: Sun, 02 Apr 2006 18:01:53 +0000 (UTC) From: Tor Egge <Tor.Egge@cvsup.no.freebsd.org> To: peter@holm.cc Cc: truckman@freebsd.org, current@freebsd.org Subject: Re: Livelock / softdep_flush "loop" Message-ID: <20060402.180153.74658240.Tor.Egge@cvsup.no.freebsd.org> In-Reply-To: <20060402094431.GA81954@peter.osted.lan> References: <20060402094431.GA81954@peter.osted.lan>
next in thread | previous in thread | raw e-mail | index | archive | help
----Next_Part(Sun_Apr__2_18:01:53_2006_708)--
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
> I managed to zoom in on the livelocks I've been seeing lately.
According to the console log, process 708 has marked one dependency as being in
progress, locked a vnode and then slept waiting for the softdep lock.
softdep_flush() doesn't take into account that some of the remaining
dependencies cannot be processed at once.
Process 45 ended up looping inside softdep_flush(), never sleeping, always
believing that more work could be done.
The enclosed patch might help.
- Tor Egge
----Next_Part(Sun_Apr__2_18:01:53_2006_708)--
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline; filename="softdep.diff2"
Index: sys/ufs/ffs/ffs_softdep.c
===================================================================
RCS file: /home/ncvs/src/sys/ufs/ffs/ffs_softdep.c,v
retrieving revision 1.193
diff -u -r1.193 ffs_softdep.c
--- sys/ufs/ffs/ffs_softdep.c 12 Mar 2006 05:25:16 -0000 1.193
+++ sys/ufs/ffs/ffs_softdep.c 2 Apr 2006 17:21:13 -0000
@@ -718,6 +718,7 @@
{
struct mount *nmp;
struct mount *mp;
+ struct ufsmount *ump;
struct thread *td;
int remaining;
int vfslocked;
@@ -752,7 +753,9 @@
continue;
vfslocked = VFS_LOCK_GIANT(mp);
softdep_process_worklist(mp, 0);
- remaining += VFSTOUFS(mp)->softdep_on_worklist;
+ ump = VFSTOUFS(mp);
+ remaining += ump->softdep_on_worklist -
+ ump->softdep_on_worklist_inprogress;
VFS_UNLOCK_GIANT(vfslocked);
mtx_lock(&mountlist_mtx);
nmp = TAILQ_NEXT(mp, mnt_list);
@@ -914,11 +917,13 @@
if ((flags & LK_NOWAIT) == 0 || wk->wk_type != D_DIRREM)
break;
wk->wk_state |= INPROGRESS;
+ ump->softdep_on_worklist_inprogress++;
FREE_LOCK(&lk);
ffs_vget(mp, WK_DIRREM(wk)->dm_oldinum,
LK_NOWAIT | LK_EXCLUSIVE, &vp);
ACQUIRE_LOCK(&lk);
wk->wk_state &= ~INPROGRESS;
+ ump->softdep_on_worklist_inprogress--;
if (vp != NULL)
break;
}
Index: sys/ufs/ufs/ufsmount.h
===================================================================
RCS file: /home/ncvs/src/sys/ufs/ufs/ufsmount.h,v
retrieving revision 1.36
diff -u -r1.36 ufsmount.h
--- sys/ufs/ufs/ufsmount.h 8 Mar 2006 23:43:39 -0000 1.36
+++ sys/ufs/ufs/ufsmount.h 2 Apr 2006 17:21:13 -0000
@@ -76,6 +76,7 @@
struct workhead softdep_workitem_pending; /* softdep work queue */
struct worklist *softdep_worklist_tail; /* Tail pointer for above */
int softdep_on_worklist; /* Items on the worklist */
+ int softdep_on_worklist_inprogress; /* Busy items on worklist */
int softdep_deps; /* Total dependency count */
int softdep_accdeps; /* accumulated dep count */
int softdep_req; /* Wakeup when deps hits 0. */
----Next_Part(Sun_Apr__2_18:01:53_2006_708)----
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20060402.180153.74658240.Tor.Egge>