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 ) id 1QPJtL-0003Yw-0M for garchives@archives.gentoo.org; Wed, 25 May 2011 19:37:15 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 3D2481C10D; Wed, 25 May 2011 19:35:10 +0000 (UTC) Received: from mail-vw0-f53.google.com (mail-vw0-f53.google.com [209.85.212.53]) by pigeon.gentoo.org (Postfix) with ESMTP id F03831C10D for ; Wed, 25 May 2011 19:35:09 +0000 (UTC) Received: by vws13 with SMTP id 13so7518210vws.40 for ; Wed, 25 May 2011 12:35:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:in-reply-to:references:from :date:x-google-sender-auth:message-id:subject:to:content-type; bh=qT0i35lJWXHVB1PSQsKCbu0p+s/2gs/pJbTv90j56WA=; b=kowxrth6mpHcU66sc4qQMIHiaRIBwQ+5/a7yX/ZRTyaDoValQQjTm3FQD552GswZBE DoQcBIIAUK6CqTLfs6A3l8gq9xPfN55Kr+bYVbXgZlctJHx/+jAb98+lb8UpvDUvBC6U GlITv3rjESsr1aCn0jX0SR42UIL3LbATCKp9E= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:content-type; b=N6XOGvw6YG4Af9XQ8aZZSxaTe2TbxfNWA3Tr6jibieZKyjT/VlVnGaXa7zvYAKe533 Fdn+zdnKdJnlQDdN6prnxVeRbS7oNFmzeNtpMFdPYVTqnNAZ72gJ6N0urn0vb3aLakHz NLV8w7nvreguQFCqaASvV1YtaGrsAplPUVjHQ= Received: by 10.52.0.136 with SMTP id 8mr7959912vde.45.1306352109173; Wed, 25 May 2011 12:35:09 -0700 (PDT) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Sender: paul.hartman@gmail.com Received: by 10.52.157.234 with HTTP; Wed, 25 May 2011 12:34:49 -0700 (PDT) In-Reply-To: <3411637.6h55QLqd4n@localhost> References: <201105251621.00659.wonko@wonkology.org> <3411637.6h55QLqd4n@localhost> From: Paul Hartman Date: Wed, 25 May 2011 14:34:49 -0500 X-Google-Sender-Auth: RzxUp4fWmM0DwKiVPN5O2fte0Y0 Message-ID: Subject: Re: [gentoo-user] Swap performance To: gentoo-user@lists.gentoo.org Content-Type: text/plain; charset=ISO-8859-1 X-Archives-Salt: X-Archives-Hash: d30d6a0947abfab0c155c7ee1ed353e8 On Wed, May 25, 2011 at 11:58 AM, Volker Armin Hemmann wrote: > On Wednesday 25 May 2011 10:31:19 Paul Hartman wrote: > >> When I move the swap to a slow SD card instead (2MB/sec transfer >> rate), even in that slow device, swapoff on the eMMC swap partition >> with ~500M in-use takes about 2 or 3 minutes at most with the data >> being swapped slowly into the SD card. >> >> So I think in your case it should be much faster than that! > > you are comparing apples with oranges (harddisks with moving arms with solid > state devices). > > Do yourself a favour. Look up how long a harddisk needs to position its head. Yeah, measuring speed in microseconds versus milliseconds. :) My SD read/write speed is about 0.9MB/sec in benchmark, and about 2 MB/sec in real-life swap usage. Based on Alex's timings it seems his HDD is getting about 0.5 MB/sec in swap usage. HDD benchmark random read/write is usually faster than that. But probably you're right and the seek operations are really killing it. HDD is about 20 times slower than SD card in seeking. If he has a USB flash drive, or memory card reader, he can use it for swap and see if it's any better or worse. I am curious how it will compare. Or, if he has multiple disks, he could create more swap partitions with equal priority and kernel will stripe/load balance automatically, hopefully improving his swap performance. Or better yet, figure out why his system is swapping at all which is what he was going for I think. With 8 GB I think he should be able to disable swap entirely anyway. :)