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]
Message-ID: <20150527082018.GB25575@lst.de>
Date:	Wed, 27 May 2015 10:20:18 +0200
From:	Christoph Hellwig <hch@....de>
To:	device-mapper development <dm-devel@...hat.com>,
	Alasdair G Kergon <agk@...hat.com>,
	Mike Snitzer <snitzer@...hat.com>,
	Ming Lei <ming.lei@...onical.com>, Al@...hat.com,
	Christoph Hellwig <hch@....de>,
	Lars Ellenberg <drbd-dev@...ts.linbit.com>, Oleg@...hat.com,
	Philip Kelleher <pjk1939@...ux.vnet.ibm.com>,
	Joshua Morris <josh.h.morris@...ibm.com>,
	Christoph Hellwig <hch@...radead.org>, Kent@...hat.com,
	Overstreet <kent.overstreet@...il.com>,
	Nitin Gupta <ngupta@...are.org>,
	Drokin <oleg.drokin@...el.com>, Viro <viro@...iv.linux.org.uk>,
	Dave Chinner <dchinner@...hat.com>, Ming Lin <mlin@...nel.org>,
	Jens Axboe <axboe@...nel.dk>,
	Andreas Dilger <andreas.dilger@...el.com>,
	Geoff Levand <geoff@...radead.org>,
	Jiri Kosina <jkosina@...e.cz>,
	lkml <linux-kernel@...r.kernel.org>, Jim Paris <jim@...n.com>,
	Minchan Kim <minchan@...nel.org>,
	Dongsu Park <dpark@...teo.net>, drbd-user@...ts.linbit.com
Subject: Re: [dm-devel] [PATCH v4 01/11] block: make generic_make_request
	handle arbitrarily sized bios

On Wed, May 27, 2015 at 01:40:22AM +0100, Alasdair G Kergon wrote:
> It does sometimes make a significant difference to device-mapper stacks.
> DM only uses it for performance reasons - it can already split bios when
> it needs to.  I tried to remove merge_bvec_fn from DM several years ago but
> couldn't because of the adverse performance impact of lots of splitting activity.

Does it still?  Since the move to immutable biovecs the bio splits are
pretty cheap now, but I'd really like to see this verified by benchmarks.
--
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/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ