diff options
| author | Andres Salomon <dilinger@queued.net> | 2009-02-11 13:27:02 -0800 |
|---|---|---|
| committer | David Woodhouse <David.Woodhouse@intel.com> | 2009-02-14 08:59:04 +0000 |
| commit | efab0b5d3eed6aa71f8e3233e4e11774eedc04dc (patch) | |
| tree | 79906754c394f0e2e081c150ea4494a3bde1b086 | |
| parent | ab00d68276295a1b4da7ad924a35a3566e9c2698 (diff) | |
[JFFS2] force the jffs2 GC daemon to behave a bit better
I've noticed some pretty poor behavior on OLPC machines after bootup, when
gdm/X are starting. The GCD monopolizes the scheduler (which in turns
means it gets to do more nand i/o), which results in processes taking much
much longer than they should to start.
As an example, on an OLPC machine going from OFW to a usable X (via
auto-login gdm) takes 2m 30s. The majority of this time is consumed by
the switch into graphical mode. With this patch, we cut a full 60s off of
bootup time. After bootup, things are much snappier as well.
Note that we have seen a CRC node error with this patch that causes the machine
to fail to boot, but we've also seen that problem without this patch.
Signed-off-by: Andres Salomon <dilinger@debian.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
| -rw-r--r-- | fs/jffs2/background.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c index 3cceef4ad2b7..e9580104b6ba 100644 --- a/fs/jffs2/background.c +++ b/fs/jffs2/background.c @@ -95,13 +95,17 @@ static int jffs2_garbage_collect_thread(void *_c) spin_unlock(&c->erase_completion_lock); - /* 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(); + /* Problem - immediately after bootup, the GCD spends a lot + * of time in places like jffs2_kill_fragtree(); so much so + * that userspace processes (like gdm and X) are starved + * despite plenty of cond_resched()s and renicing. Yield() + * doesn't help, either (presumably because userspace and GCD + * are generally competing for a higher latency resource - + * disk). + * This forces the GCD to slow the hell down. Pulling an + * inode in with read_inode() is much preferable to having + * the GC thread get there first. */ + schedule_timeout_interruptible(msecs_to_jiffies(50)); /* Put_super will send a SIGKILL and then wait on the sem. */ |