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authorAndres Salomon <dilinger@queued.net>2009-02-11 13:27:02 -0800
committerDavid Woodhouse <David.Woodhouse@intel.com>2009-02-14 08:59:04 +0000
commitefab0b5d3eed6aa71f8e3233e4e11774eedc04dc (patch)
tree79906754c394f0e2e081c150ea4494a3bde1b086
parentab00d68276295a1b4da7ad924a35a3566e9c2698 (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.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c
index 3cceef4ad2b..e9580104b6b 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.
*/