linux-kernel - Re: [PATCH v6] block: loop: avoiding too many pending per work I/O

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Date:	Fri, 1 May 2015 11:47:13 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Christoph Hellwig <hch@...radead.org>
Cc:	Ming Lei <ming.lei@...onical.com>, Jens Axboe <axboe@...nel.dk>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Justin M. Forbes" <jforbes@...oraproject.org>,
	Jeff Moyer <jmoyer@...hat.com>, "v4.0" <stable@...r.kernel.org>
Subject: Re: [PATCH v6] block: loop: avoiding too many pending per work I/O

On Fri, May 01, 2015 at 08:05:45AM -0700, Christoph Hellwig wrote:
> > Maybe just cap max_active to NR_OF_LOOP_DEVS * 16 or sth?  But idk,
> > how many concurrent workers are we talking about and why are we
> > capping per-queue concurrency from worker pool side instead of command
> > tag side?
> 
> Also we probably should have per device workqueues to start with..

Yeah, that's an option.  The only thing is that each workqueue would
have to be tagged WQ_RESCUER and end up with separate rescuer task,
which usually isn't big a deal but there are setups where a lot of
loop devices are used and it may sting a bit.

Thanks.

-- 
tejun
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