On Sat, Nov 24, 2012 at 6:21 AM, Jeff Chua <jeff.chua.linux@xxxxxxxxx> wrote: > On Fri, Nov 23, 2012 at 9:24 PM, Jens Axboe <axboe@xxxxxxxxx> wrote: >> On 2012-11-22 20:21, Linus Torvalds wrote: >>> Doesn't sound like a fsdevel issue since it seems to be independent of >>> filesystems. More like some generic block layer thing. Adding Jens >>> (and quoting the whole thing) >>> >>> Jens, any ideas? Most of your stuff came in after -rc2, which would >>> fit with the fact that most of the slowdown seems to be after -rc2 >>> according to Jeff. >> >> No ideas. Looking at what went in from my side, only the rq plug sorting >> is a core change, and that should not cause any change in behaviour for >> a single device. That's commit 975927b9. >> >>> Jeff, more bisecting would be good, though. >> >> Probably required, yes... > > > This one slows mount from 0.012s to 0.168s. > > commit 62ac665ff9fc07497ca524bd20d6a96893d11071 > Author: Mikulas Patocka <mpatocka@xxxxxxxxxx> > Date: Wed Sep 26 07:46:43 2012 +0200 > > blockdev: turn a rw semaphore into a percpu rw semaphore > > > There were couple of more changes to percpu-rw-semaphores after > 3.7.0-rc2 and those slows mount further from 0.168s to 0.500s. I don't > really know, but I'm suspecting these. Still bisecting. > > commit 5c1eabe68501d1e1b1586c7f4c46cc531828c4ab > Author: Mikulas Patocka <mpatocka@xxxxxxxxxx> > Date: Mon Oct 22 19:37:47 2012 -0400 > > percpu-rw-semaphores: use light/heavy barriers > > > commit 1bf11c53535ab87e3bf14ecdf6747bf46f601c5d > Author: Mikulas Patocka <mpatocka@xxxxxxxxxx> > Date: Mon Oct 22 19:39:16 2012 -0400 > > percpu-rw-semaphores: use rcu_read_lock_sched I reverted these 3 patches and mount time is now 0.012s. # time mount /dev/sda1 /mnt; sync; sync; umount /mnt > commit 1a25b1c4ce189e3926f2981f3302352a930086db > Author: Mikulas Patocka <mpatocka@xxxxxxxxxx> > Date: Mon Oct 15 17:20:17 2012 -0400 > > Lock splice_read and splice_write functions Looks like this one is not the problem. But I reverted it anyway because it's part of the same chunk. Happy Thanksgiving! Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
