linux-kernel - Re: [dm-devel] [PATCH v2 0/2] Introduce the bulk IV mode for improving the crypto engine efficiency

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Message-ID: <20160112234025.GF6588@sirena.org.uk>
Date:	Tue, 12 Jan 2016 23:40:25 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Mikulas Patocka <mpatocka@...hat.com>
Cc:	device-mapper development <dm-devel@...hat.com>,
	Milan Broz <gmazyland@...il.com>, Jens Axboe <axboe@...nel.dk>,
	keith.busch@...el.com, linux-raid@...r.kernel.org,
	martin.petersen@...cle.com, Mike Snitzer <snitzer@...hat.com>,
	Baolin Wang <baolin.wang@...aro.org>,
	linux-block@...r.kernel.org, neilb@...e.com,
	LKML <linux-kernel@...r.kernel.org>, sagig@...lanox.com,
	Arnd Bergmann <arnd@...db.de>, tj@...nel.org,
	dan.j.williams@...el.com,
	Kent Overstreet <kent.overstreet@...il.com>,
	Alasdair G Kergon <agk@...hat.com>
Subject: Re: [dm-devel] [PATCH v2 0/2] Introduce the bulk IV mode for
 improving the crypto engine efficiency

On Tue, Jan 12, 2016 at 06:31:19PM -0500, Mikulas Patocka wrote:
> On Mon, 4 Jan 2016, Mark Brown wrote:

> > The main thing the out of tree req-dm-crypt code is doing was using a
> > larger block size which does seem like a reasonable thing to allow
> > people to tune for performance tradeofffs but I undertand that's a lot
> > harder to achieve in a good way than one might hope.

> But as Milan pointed out, that larger block size doesn't work if you 
> process requests with different sizes - the data encrypted with one 
> request size won't match if you decrypt them with a different request 
> size.

Sure, you need to fix that block size.

> Does the hardware encryption you are optimizing for allow setting 
> arbitrary tweaks in XTS mode? What is the specific driver you are 
> optimizing for?

This isn't targeted at a specific driver or system, it's trying to make
dm-crypt better able to make use of hardware acceleration in general.

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