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author | David Woodhouse <dwmw2@infradead.org> | 2007-03-08 10:28:30 +0000 |
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committer | David Woodhouse <dwmw2@infradead.org> | 2007-03-08 10:28:30 +0000 |
commit | f8a922c7bb4d93bd84b7371a8e2571e667d2afb5 (patch) | |
tree | 3c412fe0a57cfd222e2a4b63f5599e5a2a08f08f /fs/jffs2 | |
parent | 89e2bf61da9d7664293a57100a419f8116252607 (diff) | |
download | kernel_samsung_espresso10-f8a922c7bb4d93bd84b7371a8e2571e667d2afb5.zip kernel_samsung_espresso10-f8a922c7bb4d93bd84b7371a8e2571e667d2afb5.tar.gz kernel_samsung_espresso10-f8a922c7bb4d93bd84b7371a8e2571e667d2afb5.tar.bz2 |
[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/jffs2')
-rw-r--r-- | 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. */ |