Btrfs devel - Mar 2013 - BTRFS and "ionice"

Hi,

I use "ionice -c 3 <command>" to run some low-priority
background tasks
(i.e. tar, big file copies, or performing checksums sur very big files)
using the disk "only when idle", which would be supposed to have very
little impact on my system performance meanwhile.

I can be pretty sure that those tasks are I/O-bound and use very little
CPU (and they are niced as well, anyway).

However, when such tasks are running my BTRFS system slows down to a
crawl, becomes very very unresponsive, and it seems to me that disk I/O
is completely saturated (LED is fixed lit...)

So I wonder if BTRFS correctly support ionice, or if it''s plain useless
?

TIA

Kind regards.

-- 
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
Ne cherchez pas : Je ne suis pas sur Facebook.

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Hi,
Which IO scheduler do you use? I used to have terrible read
performance during a btrfs scrub until I switched the disk scheduler
from deadline to cfq.
Cheers, Dan


On Mon, Mar 11, 2013 at 11:26 AM, Swâmi Petaramesh <swami@petaramesh.org>
wrote:
> Hi,
>
> I use "ionice -c 3 <command>" to run some low-priority
background tasks
> (i.e. tar, big file copies, or performing checksums sur very big files)
> using the disk "only when idle", which would be supposed to have
very
> little impact on my system performance meanwhile.
>
> I can be pretty sure that those tasks are I/O-bound and use very little
> CPU (and they are niced as well, anyway).
>
> However, when such tasks are running my BTRFS system slows down to a
> crawl, becomes very very unresponsive, and it seems to me that disk I/O
> is completely saturated (LED is fixed lit...)
>
> So I wonder if BTRFS correctly support ionice, or if it''s plain
useless ?
>
> TIA
>
> Kind regards.
>
> --
> Swāmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP
9076E32E
> Ne cherchez pas : Je ne suis pas sur Facebook.
>
> --
> To unsubscribe from this list: send the line "unsubscribe
linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
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