linux-kernel - Re: [PATCH RFC - TAKE TWO - 12/12] block, bfq: boost the throughput with random I/O on NCQ-capable HDDs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 30 May 2014 11:51:05 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Paolo Valente <paolo.valente@...more.it>
Cc:	Jens Axboe <axboe@...nel.dk>, Li Zefan <lizefan@...wei.com>,
	Fabio Checconi <fchecconi@...il.com>,
	Arianna Avanzini <avanzini.arianna@...il.com>,
	Paolo Valente <posta_paolo@...oo.it>,
	linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, cgroups@...r.kernel.org
Subject: Re: [PATCH RFC - TAKE TWO - 12/12] block, bfq: boost the throughput
 with random I/O on NCQ-capable HDDs

On Thu, May 29, 2014 at 11:05:43AM +0200, Paolo Valente wrote:
> This patch is basically the counterpart of patch 13 for NCQ-capable
> rotational devices. Exactly as patch 13 does on flash-based devices
> and for any workload, this patch disables device idling on rotational
> devices, but only for random I/O. More precisely, idling is disabled
> only for constantly-seeky queues (see patch 7). In fact, only with
> these queues disabling idling boosts the throughput on NCQ-capable
> rotational devices.
> 
> To not break service guarantees, idling is disabled for NCQ-enabled
> rotational devices and constantly-seeky queues only when the same
> symmetry conditions as in patch 13, plus an additional one, hold. The
> additional condition is related to the fact that this patch disables
> idling only for constantly-seeky queues. In fact, should idling be

Wouldn't it make more sense to limit queue depth to one unless the
workload can clearly benefit from allowing higher queue depth?  And I
really think it'd bring more clarity if we just concentrate on
rotational devices.

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/