linux-kernel - Re: [PATCHSET v5] Make background writeback great again for the first time

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Date:	Mon, 16 May 2016 09:47:41 +0200
From:	Jan Kara <jack@...e.cz>
To:	Jens Axboe <axboe@...nel.dk>
Cc:	Jan Kara <jack@...e.cz>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
	dchinner@...hat.com, sedat.dilek@...il.com
Subject: Re: [PATCHSET v5] Make background writeback great again for the
 first time

On Fri 13-05-16 12:29:10, Jens Axboe wrote:
> Thanks Jan, this is great and super useful! I'm revamping certain parts of
> it to deal with write back caching better, and I'll take a look at the
> regressions that you reported.
> 
> What kind of SSD is this? I'm assuming it's SATA (QD=32), and then it would
> probably be a safe assumption that it's flagging itself as having a volatile
> write back cache, would that be a correct assumption?

Yes, it is SATA with writeback cache.

> Are you using scsi-mq, or do you have an IO scheduler attached to it?

The disk was using IO scheduler, however at this point I'm not 100% sure
which scheduler (deadline or cfq) was the default one for the distro that
was installed. The machine is currently testing something else so I cannot
reinstall it and check. Maybe I can rerun some tests later in the week when
the machine gets freed with scsi-mq or deadline IO scheduler so that we
have 100% certain config.

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