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 HWdea_-4qhnt for ; Mon, 18 Mar 2013 11:44:02 +0100 (CET) Received: from awesome.dsw2k3.info (awesome.dsw2k3.info [IPv6:2a01:198:661:1f::3]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.saout.de (Postfix) with ESMTPS for ; Mon, 18 Mar 2013 11:44:02 +0100 (CET) Received: from localhost (localhost.localdomain [127.0.0.1]) by awesome.dsw2k3.info (Postfix) with ESMTP id 4C561C0F1A for ; Mon, 18 Mar 2013 11:44:02 +0100 (CET) Received: from awesome.dsw2k3.info ([127.0.0.1]) by localhost (awesome.dsw2k3.info [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id h3YAcN1yWFT5 for ; Mon, 18 Mar 2013 11:44:01 +0100 (CET) Received: from citd.de (p50813F8F.dip.t-dialin.net [80.129.63.143]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by awesome.dsw2k3.info (Postfix) with ESMTPSA for ; Mon, 18 Mar 2013 11:44:01 +0100 (CET) Date: Mon, 18 Mar 2013 11:43:59 +0100 From: Matthias Schniedermeyer Message-ID: <20130318104359.GA8350@citd.de> References: <20130317225516.GA6053@citd.de> <20130318083700.GA28049@citd.de> <20130318100148.GA1399@fancy-poultry.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130318100148.GA1399@fancy-poultry.org> Subject: Re: [dm-crypt] unusual writing speeds when benchmark speeds are high enough List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de On 18.03.2013 11:01, Heinz Diehl wrote: > On 18.03.2013, Matthias Schniedermeyer wrote: > > > The SSD i have can reach (with encryption) about 400MB/s, but that is > > best-case performance when all moons are aligned. I haven't really > > benchmarked the real-world performance, the dd-example (with conv=fsync) > > only got 88MB/s. > > On all my SSD disks, cryptsetup performance is not even near that. I > have about 450 MB/s without encryption, and max. 120 MB/s with. SSD performance has more 'it depends' than anything else. It isn't funny. ;-) But as i don't need my SSDs for write-heavy linear performance (much), the much better random-write rate than HDDs still make them worthwile. And the much better (random) read performance is the icing. Overwriting appers to have better performance, but that is nothing i would do regularly. dd if=/dev/zero of=zero bs=1M count=10k oflag=direct 10737418240 bytes (11 GB) copied, 116.629 s, 92.1 MB/s dd if=/dev/zero of=zero bs=1M count=10k oflag=direct conv=notrunc 10737418240 bytes (11 GB) copied, 50.3905 s, 213 MB/s dd if=/dev/zero of=zero bs=1M count=10k oflag=direct conv=notrunc 10737418240 bytes (11 GB) copied, 51.0608 s, 210 MB/s My previous SSD with a Sandforce controller had much worse "worst case" performance as the Sandforce controller really doesn't like incompressible data and encrypted data looks like (or at least should look like) incompressible random-data. -- Matthias