From: NeilBrown <neilb@suse.de>
Date: Fri, 13 Aug 2010 11:56:49 +0000 (+1000)
Subject: Tune checkpoint freq by segments, not blocks.
X-Git-Url: http://git.neil.brown.name/?a=commitdiff_plain;h=83fe3bbdeda0ec48aea96bc216cb4cb041ca9660;p=LaFS.git

Tune checkpoint freq by segments, not blocks.

If nothing else does, we should force a checkpoint
every few segments rather than every so-many blocks.

Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/checkpoint.c b/checkpoint.c
index baf4e23..8eccf47 100644
--- a/checkpoint.c
+++ b/checkpoint.c
@@ -508,7 +508,7 @@ static void finish_checkpoint(struct fs *fs, int youth)
 	fs->cleaner.cleaning = 0;
 
 	fs->checkpoint_youth = youth;
-	fs->newblocks = 0;
+	fs->newsegments = 0;
 	lafs_wake_thread(fs);
 }
 
@@ -519,7 +519,7 @@ unsigned long lafs_do_checkpoint(struct fs *fs)
 	    !test_bit(FinalCheckpoint, &fs->fsstate)) {
 		/* not compulsory, but maybe just time */
 		if (fs->cleaner.active == 0 &&
-		    fs->newblocks > fs->max_newblocks)
+		    fs->newsegments > fs->max_newsegs)
 			set_bit(CheckpointNeeded, &fs->fsstate);
 	}
 
diff --git a/cluster.c b/cluster.c
index bf46087..0f3e2eb 100644
--- a/cluster.c
+++ b/cluster.c
@@ -445,6 +445,10 @@ static int new_segment(struct fs *fs, int cnum)
 	BUG_ON(wc->seg.dev != dev);
 	BUG_ON(wc->seg.num != seg);
 
+	if (cnum == 0)
+		/* wc mutex protects us here */
+		fs->newsegments++;
+
 	return 0;
 }
 
@@ -1192,8 +1196,6 @@ static void cluster_flush(struct fs *fs, int cnum)
 			lafs_allocated_block(fs, b, addr);
 		blocks++;
 	}
-	if (cnum == 0)
-		fs->newblocks += blocks;
 
 	if (head_start)
 		cluster_closehead(wc, head_start);
diff --git a/state.h b/state.h
index 0489fbe..ee37bec 100644
--- a/state.h
+++ b/state.h
@@ -141,11 +141,8 @@ struct fs {
 	} cleaner;
 	struct task_struct *thread;
 
-	unsigned long newblocks;	/* number of blocks written since checkpoint
-					 * FIXME this should probably be a count
-					 * of segments (?)
-					 */
-	unsigned long max_newblocks;	/* max blocks in a checkpoint (roughly) */
+	unsigned long newsegments;	/* number of segments written since checkpoint */
+	unsigned long max_newsegs;	/* max segments in a checkpoint (roughly) */
 
 	/* counters for (pre)allocating space. */
 	spinlock_t alloc_lock;
diff --git a/super.c b/super.c
index 7faf067..6c0c32d 100644
--- a/super.c
+++ b/super.c
@@ -574,9 +574,7 @@ lafs_load(struct fs *fs, struct options *op, int newest)
 		fs->wc[i].seg.dev = -1;
 	}
 
-	fs->max_newblocks = 1000; /* FIXME this should be configurable, and
-				   * guessed better
-				   */
+	fs->max_newsegs = 32; /* FIXME this should be configurable */
 
 	err = -ENOMEM;
 	fs->devs = kzalloc(sizeof(struct fs_dev)*fs->devices, GFP_KERNEL);