linux-kernel - Re: [PATCH] block: export SSD/non-rotational queue flag through sysfs

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] [day] [month] [year] [list]

Date:	Tue, 3 Feb 2009 13:32:42 +0100
From:	Pierre Ossman <drzeus-list@...eus.cx>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	Hugh Dickins <hugh@...itas.com>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Grant Grundler <grundler@...gle.com>,
	Greg Freemyer <greg.freemyer@...il.com>,
	Tejun Heo <htejun@...il.com>, Michael Tokarev <mjt@....msk.ru>,
	Kay Sievers <kay.sievers@...y.org>,
	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH] block: export SSD/non-rotational queue flag through
 sysfs

On Fri, 16 Jan 2009 07:48:18 +0100
Jens Axboe <jens.axboe@...cle.com> wrote:

> 
> For non-queuing devices, I think our current check is a bit too drastic.
> We probably want to change that to
> 
> int dont_plug(q)
> {
>         return blk_queue_nonrot(q) && blk_queue_tagged(q);
> }
> 

Please do. The MMC block driver sets nonrot as of late, but it is
extremely dependent on merging. The command overhead is just silly, so
to get anywhere near the speed numbers indicated in marketing you need
large requests.

It seems that too many confuse "non-rotational" with "low latency",
which isn't always the same. :)

Rgds
-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  rdesktop, core developer          http://www.rdesktop.org

  WARNING: This correspondence is being monitored by the
  Swedish government. Make sure your server uses encryption
  for SMTP traffic and consider using PGP for end-to-end
  encryption.

Download attachment "signature.asc" of type "application/pgp-signature" (198 bytes)