From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from <gentoo-user+bounces-136255-garchives=archives.gentoo.org@lists.gentoo.org>) id 1S7Wy7-0007zd-Bc for garchives@archives.gentoo.org; Tue, 13 Mar 2012 19:01:11 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 901CBE097B; Tue, 13 Mar 2012 19:00:47 +0000 (UTC) Received: from out1-smtp.messagingengine.com (out1-smtp.messagingengine.com [66.111.4.25]) by pigeon.gentoo.org (Postfix) with ESMTP id 6FD06E0980 for <gentoo-user@lists.gentoo.org>; Tue, 13 Mar 2012 18:59:03 +0000 (UTC) Received: from compute5.internal (compute5.nyi.mail.srv.osa [10.202.2.45]) by gateway1.nyi.mail.srv.osa (Postfix) with ESMTP id 2DD9320CB3 for <gentoo-user@lists.gentoo.org>; Tue, 13 Mar 2012 14:59:03 -0400 (EDT) Received: from frontend2.nyi.mail.srv.osa ([10.202.2.161]) by compute5.internal (MEProxy); Tue, 13 Mar 2012 14:59:03 -0400 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=binarywings.net; h=message-id:date:from:mime-version:to:subject:references :in-reply-to:content-type; s=mesmtp; bh=fJvF2HeAG8RdvrOqcYdkp2zY BVc=; b=o3msdNqPI79CYzy5SJwR0oGb8eXiBFjwmbznU6mqyVtvGx6KkMH4MV2h psSiJIUVULJVctS4TTEi9P/Et0wynSvZRhcD34UElOcLqfPONSjPBVDKbbcuoK8r X8PvKI90vK0qucHZOxEm/Cdrntgpx9wPTB2DS78k5BbvxFIXG30= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=message-id:date:from:mime-version:to :subject:references:in-reply-to:content-type; s=smtpout; bh=fJvF 2HeAG8RdvrOqcYdkp2zYBVc=; b=G7oZZSbRoAGevOourt1XVKt/KM2Nv1c4NHYr sdqRPo2lchOQtBGbJ4jksOZZsicqkvpUfJrE7gIcUhDfSKwfVS92C44M2/+3dRWv H4MME3RZmnFZBi9hPt88Z415owKJdGxhf8UhenBDOcnXszJa9/xTko1rLXbXn1JN U+WfIYc= X-Sasl-enc: j7ttYfwIhES3Zofr6j7YIkFyfRXCFV0ISd8Gx4O7qMdv 1331665142 Received: from [192.168.5.18] (serv.binarywings.net [83.169.5.6]) by mail.messagingengine.com (Postfix) with ESMTPSA id E39124824EE for <gentoo-user@lists.gentoo.org>; Tue, 13 Mar 2012 14:59:01 -0400 (EDT) Message-ID: <4F5F98EF.6050704@binarywings.net> Date: Tue, 13 Mar 2012 19:58:55 +0100 From: Florian Philipp <lists@binarywings.net> User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120303 Thunderbird/10.0.1 Precedence: bulk List-Post: <mailto:gentoo-user@lists.gentoo.org> List-Help: <mailto:gentoo-user+help@lists.gentoo.org> List-Unsubscribe: <mailto:gentoo-user+unsubscribe@lists.gentoo.org> List-Subscribe: <mailto:gentoo-user+subscribe@lists.gentoo.org> List-Id: Gentoo Linux mail <gentoo-user.gentoo.org> X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] hard drive encryption References: <4F5CC6F5.6020303@gmail.com> <4F5CEF0D.5050801@binarywings.net> <4F5F35C1.8070301@gmail.com> <4F5F71C3.6070206@binarywings.net> <20120313174555.GA15334@eisen.lan> <4F5F8CC3.7070402@binarywings.net> <CA+czFiCcDMz7nMhfabGL6iRL4ecd+cxWdhu3ZeGSQeJf_MKM1Q@mail.gmail.com> In-Reply-To: <CA+czFiCcDMz7nMhfabGL6iRL4ecd+cxWdhu3ZeGSQeJf_MKM1Q@mail.gmail.com> X-Enigmail-Version: 1.3.5 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigA4D4C42DB3C40201D513D738" X-Archives-Salt: 92241c44-a04f-4c86-92c6-22d48881588e X-Archives-Hash: 3fee7b0788da385665c6e25a94b80d6d This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigA4D4C42DB3C40201D513D738 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Am 13.03.2012 19:18, schrieb Michael Mol: > On Tue, Mar 13, 2012 at 2:06 PM, Florian Philipp <lists@binarywings.net= > wrote: >> Am 13.03.2012 18:45, schrieb Frank Steinmetzger: >>> On Tue, Mar 13, 2012 at 05:11:47PM +0100, Florian Philipp wrote: >>> >>>>> Since I am planning to encrypt only home/ under LVM control, what k= ind >>>>> of overhead should I expect? >>>> >>>> What do you mean with overhead? CPU utilization? In that case the >>>> overhead is minimal, especially when you run a 64-bit kernel with th= e >>>> optimized AES kernel module. >>> >>> Speaking of that... >>> I always wondered what the exact difference was between AES and AES i= 586. I >>> can gather myself that it's about optimisation for a specific archite= cture. >>> But which one would be best for my i686 Core 2 Duo? >> >> From what I can see in the kernel sources, there is a generic AES >> implementation using nothing but portable C code and then there is >> "aes-i586" assembler code with "aes_glue" C code. >=20 >=20 >> So I assume the i586 >> version is better for you --- unless GCC suddenly got a lot better at >> optimizing code. >=20 > Since when, exactly? GCC isn't the best compiler at optimization, but > I fully expect current versions to produce better code for x86-64 than > hand-tuned i586. Wider registers, more registers, crypto acceleration > instructions and SIMD instructions are all very nice to have. I don't > know the specifics of AES, though, or what kind of crypto algorithm it > is, so it's entirely possible that one can't effectively parallelize > it except in some relatively unique circumstances. >=20 One sec. We are talking about an Core2 Duo running in 32bit mode, right? That's what the i686 reference in the question meant --- or at least, that's what I assumed. If we talk about 32bit mode, none of what you describe is available. Those additional registers and instructions are not accessible with i686 instructions. A Core 2 also has no AES instructions. Of course, GCC could make use of what it knows about the CPU, like number of parallel pipelines, pipeline depth, cache size, instructions added in i686 and so on. But even then I doubt it can outperform hand-tuned assembler, even if it is for a slightly older instruction set.= If instead we are talking about an Core 2 Duo running in x86_64 mode, we should be talking about the aes-x86_64 module instead of the aes-i586 module and that makes use of the complete instruction set of the Core 2, including SSE2. Regards, Florian Philipp --------------enigA4D4C42DB3C40201D513D738 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk9fmPMACgkQqs4uOUlOuU/4UgCeMfVTIW3GvNAkdXzBlk/0s4VO n/wAnR9XvhrAY9zXvVN9+zVbuwyx7h4v =sIVp -----END PGP SIGNATURE----- --------------enigA4D4C42DB3C40201D513D738--