Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755977Ab1CHQpu (ORCPT ); Tue, 8 Mar 2011 11:45:50 -0500 Received: from piggy.rz.tu-ilmenau.de ([141.24.4.8]:49309 "EHLO piggy.rz.tu-ilmenau.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753051Ab1CHQpt (ORCPT ); Tue, 8 Mar 2011 11:45:49 -0500 Date: Tue, 8 Mar 2011 17:45:08 +0100 From: "Mario 'BitKoenig' Holbe" To: dm-crypt@saout.de Cc: linux-kernel@vger.kernel.org, Andi Kleen , Milan Broz , Alasdair G Kergon Subject: dm-crypt: Performance Regression 2.6.37 -> 2.6.38-rc8 Message-ID: <20110308164508.GA8729@darkside.kls.lan> Mail-Followup-To: Mario 'BitKoenig' Holbe , dm-crypt@saout.de, linux-kernel@vger.kernel.org, Andi Kleen , Milan Broz , Alasdair G Kergon MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="tThc/1wpZn/ma/RB" Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2272 Lines: 63 --tThc/1wpZn/ma/RB Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello, dm-crypt in 2.6.38 changed to per-CPU workqueues to increase it's performance by parallelizing encryption to multiple CPUs. This modification seems to cause (massive) performance drops for multiple parallel dm-crypt instances... I'm running a 4-disk RAID0 on top of 4 independent dm-crypt(aes-xts) devices on a Core2Quad 3GHz. This setup did overcome the single-CPU limitation from previous versions and utilized all 4 cores for encryption. The throughput of this array drops from 282MB/s sustained read (dd, single process) with 2.6.37.3 down to 133MB/s with 2.6.38-rc8 (which nearly equals to single-disk throughput of 128MB/s - just in case this matters). This indicates way less parallelization now with 2.6.38 than before. I don't think this was intentional :) The dm-crypt per-CPU workqueues got introduced in 2.6.38 with c029772125594e31eb1a5ad9e0913724ed9891f2 Reverting dm-crypt.c to the version before this commit re-gains the same throughput as with 2.6.37. Submitters/Signers of c029772125594e31eb1a5ad9e0913724ed9891f2 CC:ed. Thanks for your work & regards Mario --=20 There are two major products that come from Berkeley: LSD and UNIX. We don't believe this to be a coincidence. -- Jeremy S. Anderson --tThc/1wpZn/ma/RB Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQEVAwUBTXZdFBS+e2HeSPbpAQKziwf/f32YT/lMyVfgmOCVAoh7maD0O9qkYozT FRBd2S8LXJmCqUDEJnVLenYCUoDo9UeFiAZ2wQ9cekBj0KZepPTSJuopJQlMYygk 9Am771WshE6mGEvcywdm5UXX/q1ICh8+b1ykzdNw6MLsTsLMULb6vdrXxe/n76me O0SGv6haM6O8tC99MlN88gwvCBN+dQIdvVOM1cXdNfZpFouVcAaSYRgCm456Z4qV 91XKwcMeJTIVCLjNHzrFNWdPnKxiQ8egIRHJKzuwbBD1rg+JnLTqCnfEs1kvnZxL u13MTemm0aHF4sb086DQxxfQPVUDc3ceUGitKpOQSOFSOia7LmPD+w== =GgyN -----END PGP SIGNATURE----- --tThc/1wpZn/ma/RB-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/