linux-kernel - Re: [PATCH RFC - TAKE TWO - 08/12] block, bfq: preserve a low latency also with NCQ-capable drives

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Date:	Mon, 2 Jun 2014 11:58:31 +0200
From:	Paolo Valente <paolo.valente@...more.it>
To:	Tejun Heo <tj@...nel.org>
Cc:	Jens Axboe <axboe@...nel.dk>, Li Zefan <lizefan@...wei.com>,
	Fabio Checconi <fchecconi@...il.com>,
	Arianna Avanzini <avanzini.arianna@...il.com>,
	linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, cgroups@...r.kernel.org
Subject: Re: [PATCH RFC - TAKE TWO - 08/12] block, bfq: preserve a low latency also with NCQ-capable drives


Il giorno 31/mag/2014, alle ore 15:48, Tejun Heo <tj@...nel.org> ha scritto:

> On Thu, May 29, 2014 at 11:05:39AM +0200, Paolo Valente wrote:
>> This patch addresses this issue by not disabling device idling for
> 
> This patch addresses this issue by allowing device idling for...
> 
>> weight-raised queues, even if the device supports NCQ. This allows BFQ
>> to start serving a new queue, and therefore allows the drive to
> 
> This disallows BFQ to start serving a new queue, and therefore the
> drive to prefetch new requests, until the idling timeout expires.
> 
> Prefetch?  Can you elaborate?

By prefetching I meant just queuing more than one request (by the drive). I hope that this clarifies things a little bit.

Paolo

> 
> Thanks.
> 
> -- 
> tejun


--
Paolo Valente                                                 
Algogroup
Dipartimento di Fisica, Informatica e Matematica		
Via Campi, 213/B
41125 Modena - Italy        				  
homepage:  http://algogroup.unimore.it/people/paolo/

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