From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.saout.de ([127.0.0.1]) by localhost (mail.saout.de [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id AZPASwQJrMqh for ; Sun, 22 Jul 2012 21:29:33 +0200 (CEST) Received: from mail1.merlins.org (magic.merlins.org [209.81.13.136]) (using TLSv1.2 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.saout.de (Postfix) with ESMTPS for ; Sun, 22 Jul 2012 21:29:32 +0200 (CEST) Date: Sun, 22 Jul 2012 12:07:58 -0700 From: Marc MERLIN Message-ID: <20120722190757.GB10089@merlins.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [dm-crypt] aes-xts-plain with aes_x86_64 makes my SSD 5x slower than my encrypted HD List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de I got a new Samsumg 830 512GB SSD which is supposed to be very high performance. The raw device seems fast enough on a quick hdparm test: /dev/sda4: Timing cached reads: 14258 MB in 2.00 seconds = 7136.70 MB/sec Timing buffered disk reads: 1392 MB in 3.00 seconds = 463.45 MB/sec <<<< which is 4x faster than my non encrypted spinning disk, as expected. But once I encrypt it, it drops to 5 times slower than my 1TB spinning disk in the same laptop: gandalfthegreat:~# hdparm -tT /dev/mapper/ssdcrypt /dev/mapper/ssdcrypt: Timing cached reads: 15412 MB in 2.00 seconds = 7715.37 MB/sec Timing buffered disk reads: 70 MB in 3.06 seconds = 22.91 MB/sec <<<< gandalfthegreat:~# hdparm -tT /dev/mapper/cryptroot (spinning disk) /dev/mapper/cryptroot: Timing cached reads: 16222 MB in 2.00 seconds = 8121.03 MB/sec Timing buffered disk reads: 308 MB in 3.01 seconds = 102.24 MB/sec <<<< I used aes-xts-plain as recommended on http://www.mayrhofer.eu.org/ssd-linux-benchmark gandalfthegreat:~# cryptsetup status /dev/mapper/ssdcrypt /dev/mapper/ssdcrypt is active. type: LUKS1 cipher: aes-xts-plain keysize: 256 bits device: /dev/sda4 offset: 4096 sectors size: 926308752 sectors mode: read/write I tried cryptsetup luksFormat --align-payload=8192 the first time, so my offset was 8K, but that did not make a difference in speed. gandalfthegreat:~# lsmod |grep -e aes aesni_intel 50443 66 cryptd 14517 18 ghash_clmulni_intel,aesni_intel aes_x86_64 16796 1 aesni_intel Kernel: 3.4.4-amd64 gandalfthegreat:~# cryptsetup --version cryptsetup 1.4.3 I know that SSDs are weird and all, but getting a raw device speed of a mere 23MB/sec down from 463MB/s and compared to 102MB/s for a similarly spinning drive, is a problem, is it not? Any suggestions would be appreciated. Thanks, Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/