The patch titled jffs2: force the jffs2 GC daemon to behave a bit better has been added to the -mm tree. Its filename is jffs2-force-the-jffs2-gc-daemon-to-behave-a-bit-better.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: jffs2: force the jffs2 GC daemon to behave a bit better From: Andres Salomon <dilinger@xxxxxxxxxx> 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@xxxxxxxxxx> Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/jffs2/background.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff -puN fs/jffs2/background.c~jffs2-force-the-jffs2-gc-daemon-to-behave-a-bit-better fs/jffs2/background.c --- a/fs/jffs2/background.c~jffs2-force-the-jffs2-gc-daemon-to-behave-a-bit-better +++ a/fs/jffs2/background.c @@ -95,13 +95,17 @@ static int jffs2_garbage_collect_thread( 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. */ _ Patches currently in -mm which might be from dilinger@xxxxxxxxxx are jffs2-force-the-jffs2-gc-daemon-to-behave-a-bit-better.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html