linux-kernel - Re: [PATCH][RF C/T/D] Unmapped page cache control

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:	Wed, 17 Mar 2010 17:52:29 +0100
From:	Christoph Hellwig <hch@....de>
To:	Avi Kivity <avi@...hat.com>
Cc:	Chris Webb <chris@...chsys.com>, balbir@...ux.vnet.ibm.com,
	KVM development list <kvm@...r.kernel.org>,
	Rik van Riel <riel@...riel.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Christoph Hellwig <hch@....de>, Kevin Wolf <kwolf@...hat.com>
Subject: Re: [PATCH][RF C/T/D] Unmapped page cache control - via boot parameter

On Wed, Mar 17, 2010 at 06:22:29PM +0200, Avi Kivity wrote:
> They should be reorderable.  Otherwise host filesystems on several 
> volumes would suffer the same problems.

They are reordable, just not as extremly as the the page cache.
Remember that the request queue really is just a relatively small queue
of outstanding I/O, and that is absolutely intentional.  Large scale
_caching_ is done by the VM in the pagecache, with all the usual aging,
pressure, etc algorithms applied to it.  The block devices have a
relatively small fixed size request queue associated with it to
facilitate request merging and limited reordering and having fully
set up I/O requests for the device.

--
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/