To better understand performance problems with journalled soft updates,

we need to collect the highest level of allocation for each of the
different soft update dependency structures. This change collects these
statistics and makes them available using `sysctl debug.softdep.highuse'.

Reviewed by: kib
Tested by:   Peter Holm
MFC after:   2 weeks

sys/ufs/ffs/ffs_softdep.c

@@ -661,14 +661,16 @@ FEATURE(softupdates, "FFS soft-updates support");
 #define	D_LAST		D_SENTINEL
 
 unsigned long dep_current[D_LAST + 1];
+unsigned long dep_highuse[D_LAST + 1];
 unsigned long dep_total[D_LAST + 1];
 unsigned long dep_write[D_LAST + 1];
 
-
 static SYSCTL_NODE(_debug, OID_AUTO, softdep, CTLFLAG_RW, 0,
     "soft updates stats");
 static SYSCTL_NODE(_debug_softdep, OID_AUTO, total, CTLFLAG_RW, 0,
     "total dependencies allocated");
+static SYSCTL_NODE(_debug_softdep, OID_AUTO, highuse, CTLFLAG_RW, 0,
+    "high use dependencies allocated");
 static SYSCTL_NODE(_debug_softdep, OID_AUTO, current, CTLFLAG_RW, 0,
     "current dependencies allocated");
 static SYSCTL_NODE(_debug_softdep, OID_AUTO, write, CTLFLAG_RW, 0,
@@ -680,6 +682,8 @@ static SYSCTL_NODE(_debug_softdep, OID_AUTO, write, CTLFLAG_RW, 0,
 	&dep_total[D_ ## type], 0, "");					\
     SYSCTL_ULONG(_debug_softdep_current, OID_AUTO, str, CTLFLAG_RD, 	\
 	&dep_current[D_ ## type], 0, "");				\
+    SYSCTL_ULONG(_debug_softdep_highuse, OID_AUTO, str, CTLFLAG_RD, 	\
+	&dep_highuse[D_ ## type], 0, "");				\
     SYSCTL_ULONG(_debug_softdep_write, OID_AUTO, str, CTLFLAG_RD, 	\
 	&dep_write[D_ ## type], 0, "");
 
@@ -1204,8 +1208,12 @@ jwork_insert(dst, jsegdep)
  */
 static	void workitem_free(struct worklist *, int);
 static	void workitem_alloc(struct worklist *, int, struct mount *);
+static	void workitem_reassign(struct worklist *, int);
 
-#define	WORKITEM_FREE(item, type) workitem_free((struct worklist *)(item), (type))
+#define	WORKITEM_FREE(item, type) \
+	workitem_free((struct worklist *)(item), (type))
+#define	WORKITEM_REASSIGN(item, type) \
+	workitem_reassign((struct worklist *)(item), (type))
 
 static void
 workitem_free(item, type)
@@ -1219,16 +1227,22 @@ workitem_free(item, type)
 	if (item->wk_state & ONWORKLIST)
 		panic("workitem_free: %s(0x%X) still on list",
 		    TYPENAME(item->wk_type), item->wk_state);
-	if (item->wk_type != type)
+	if (item->wk_type != type && type != D_NEWBLK)
 		panic("workitem_free: type mismatch %s != %s",
 		    TYPENAME(item->wk_type), TYPENAME(type));
 #endif
 	if (item->wk_state & IOWAITING)
 		wakeup(item);
 	ump = VFSTOUFS(item->wk_mp);
+	KASSERT(ump->softdep_deps > 0,
+	    ("workitem_free: %s: softdep_deps going negative",
+	    ump->um_fs->fs_fsmnt));
 	if (--ump->softdep_deps == 0 && ump->softdep_req)
 		wakeup(&ump->softdep_deps);
-	dep_current[type]--;
+	KASSERT(dep_current[item->wk_type] > 0,
+	    ("workitem_free: %s: dep_current[%s] going negative",
+	    ump->um_fs->fs_fsmnt, TYPENAME(item->wk_type)));
+	dep_current[item->wk_type]--;
 	free(item, DtoM(type));
 }
 
@@ -1247,12 +1261,31 @@ workitem_alloc(item, type, mp)
 	ump = VFSTOUFS(mp);
 	ACQUIRE_LOCK(&lk);
 	dep_current[type]++;
+	if (dep_current[type] > dep_highuse[type])
+		dep_highuse[type] = dep_current[type];
 	dep_total[type]++;
 	ump->softdep_deps++;
 	ump->softdep_accdeps++;
 	FREE_LOCK(&lk);
 }
 
+static void
+workitem_reassign(item, newtype)
+	struct worklist *item;
+	int newtype;
+{
+
+	KASSERT(dep_current[item->wk_type] > 0,
+	    ("workitem_reassign: %s: dep_current[%s] going negative",
+	    VFSTOUFS(item->wk_mp)->um_fs->fs_fsmnt, TYPENAME(item->wk_type)));
+	dep_current[item->wk_type]--;
+	dep_current[newtype]++;
+	if (dep_current[newtype] > dep_highuse[newtype])
+		dep_highuse[newtype] = dep_current[newtype];
+	dep_total[newtype]++;
+	item->wk_type = newtype;
+}
+
 /*
  * Workitem queue management
  */
@@ -5122,7 +5155,7 @@ softdep_setup_allocdirect(ip, off, newblkno, oldblkno, newsize, oldsize, bp)
 	/*
 	 * Convert the newblk to an allocdirect.
 	 */
-	newblk->nb_list.wk_type = D_ALLOCDIRECT;
+	WORKITEM_REASSIGN(newblk, D_ALLOCDIRECT);
 	adp = (struct allocdirect *)newblk;
 	newblk->nb_freefrag = freefrag;
 	adp->ad_offset = off;
@@ -5478,7 +5511,7 @@ softdep_setup_allocext(ip, off, newblkno, oldblkno, newsize, oldsize, bp)
 	/*
 	 * Convert the newblk to an allocdirect.
 	 */
-	newblk->nb_list.wk_type = D_ALLOCDIRECT;
+	WORKITEM_REASSIGN(newblk, D_ALLOCDIRECT);
 	adp = (struct allocdirect *)newblk;
 	newblk->nb_freefrag = freefrag;
 	adp->ad_offset = off;
@@ -5587,7 +5620,7 @@ newallocindir(ip, ptrno, newblkno, oldblkno, lbn)
 		panic("new_allocindir: lost block");
 	KASSERT(newblk->nb_list.wk_type == D_NEWBLK,
 	    ("newallocindir: newblk already initialized"));
-	newblk->nb_list.wk_type = D_ALLOCINDIR;
+	WORKITEM_REASSIGN(newblk, D_ALLOCINDIR);
 	newblk->nb_freefrag = freefrag;
 	aip = (struct allocindir *)newblk;
 	aip->ai_offset = ptrno;
@@ -7218,7 +7251,9 @@ free_newblk(newblk)
 	struct worklist *wk;
 
 	KASSERT(newblk->nb_jnewblk == NULL,
-	    ("free_newblk; jnewblk %p still attached", newblk->nb_jnewblk));
+	    ("free_newblk: jnewblk %p still attached", newblk->nb_jnewblk));
+	KASSERT(newblk->nb_list.wk_type != D_NEWBLK,
+	    ("free_newblk: unclaimed newblk"));
 	rw_assert(&lk, RA_WLOCKED);
 	newblk_freefrag(newblk);
 	if (newblk->nb_state & ONDEPLIST)
@@ -7233,7 +7268,6 @@ free_newblk(newblk)
 	while ((indirdep = LIST_FIRST(&newblk->nb_indirdeps)) != NULL)
 		indirdep_complete(indirdep);
 	handle_jwork(&newblk->nb_jwork);
-	newblk->nb_list.wk_type = D_NEWBLK;
 	WORKITEM_FREE(newblk, D_NEWBLK);
 }