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

[Ming Lei]

On Fri, May 1, 2015 at 11:47 PM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> 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

I guess we have to do that because of nested loop devices.

> 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.

The work queue can be allocated just before the loop is to be used
and destroyed when it needn't.

I will figure out one patch to do that.

>
> Thanks.
>
> --
> tejun
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