Re: [PATCH 0/5] writeback: Fix bandwidth estimates

[Jan Kara <jack@suse.cz>]

On Fri 09-07-21 15:19:17, Michael Stapelberg wrote:
> Thanks for sending this patch series!
> 
> I have used the mmap.c reproducer as before, with the following parameters:
> * mkdir /tmp/mnt
> * fusermount -u /tmp/mnt; /root/fuse-2.9.9/example/fusexmp_fh -f /tmp/mnt
> * dd if=/dev/urandom of=/tmp/was bs=1M count=99
> * while :; do grep ^Bdi /sys/kernel/debug/bdi/0:44/stats; sleep 0.1; done
> * while :; do time WORKAROUND=1 ~/mmap /tmp/was
> /tmp/mnt/tmp/stapelberg.1; sleep 5; done
> 
> Previously, after a few iterations, the BdiWriteBandwidth measure
> would gradually approach 0.
> 
> With your patch series applied, the BdiWriteBandwidth is updated much
> more quickly, and converges to ≈16000 kBps.
> When I start copying more quickly, the bandwidth measure rises quickly.
> 
> As far as I understand, this should fix the problem (provided 16000
> kBps is an okay value).
> Certainly, I don’t see the downward spiral either with your patches :)

Thanks for testing! Can I add your Tested-by tag?

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR