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authorDavid Woodhouse <dwmw2@infradead.org>2007-03-08 10:28:30 +0000
committerDavid Woodhouse <dwmw2@infradead.org>2007-03-08 10:28:30 +0000
commitf8a922c7bb4d93bd84b7371a8e2571e667d2afb5 (patch)
tree3c412fe0a57cfd222e2a4b63f5599e5a2a08f08f /fs
parent89e2bf61da9d7664293a57100a419f8116252607 (diff)
[JFFS2] Use yield() between GC passes in background thread.
The garbage collection thread is strictly an optimisation. Everything it does would also be done just-in-time in the context of something in userspace trying to access the file system. Sometimes, however, it's a pessimisation. Especially during early boot when it's checksumming nodes and scanning inodes which are shortly going to be pulled in by read_inode anyway. We end up building the rbtree of node coverage twice for the same inode. By switching to yield() instead of cond_resched() in the main loop, we observe boot times on the OLPC system going down from about 100 seconds to 60. Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/jffs2/background.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c
index 6eb3daebd563..888f236e5494 100644
--- a/fs/jffs2/background.c
+++ b/fs/jffs2/background.c
@@ -99,7 +99,13 @@ static int jffs2_garbage_collect_thread(void *_c)
if (try_to_freeze())
continue;
- cond_resched();
+ /* This thread is purely an optimisation. But if it runs when
+ other things could be running, it actually makes things a
+ lot worse. Use yield() and put it at the back of the runqueue
+ every time. Especially during boot, pulling an inode in
+ with read_inode() is much preferable to having the GC thread
+ get there first. */
+ yield();
/* Put_super will send a SIGKILL and then wait on the sem.
*/