Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f8a922c7bb4d93bd84b7371a8e2571e667d2afb5
Commit: f8a922c7bb4d93bd84b7371a8e2571e667d2afb5
Parent: 89e2bf61da9d7664293a57100a419f8116252607
Author: David Woodhouse <[EMAIL PROTECTED]>
AuthorDate: Thu Mar 8 10:28:30 2007 +0000
Committer: David Woodhouse <[EMAIL PROTECTED]>
CommitDate: Thu Mar 8 10:28:30 2007 +0000
[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 <[EMAIL PROTECTED]>
---
fs/jffs2/background.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c
index 6eb3dae..888f236 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.
*/
-
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