BTRFS and "ionice"

BTRFS and "ionice"

[Swâmi Petaramesh]

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.

Re: BTRFS and "ionice"

[Dan van der Ster]

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.
>
> --
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