From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id p0ADNfF4255265 for ; Mon, 10 Jan 2011 07:23:42 -0600 Received: from mailsrv14.zmi.at (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 5E0681484EC7 for ; Mon, 10 Jan 2011 05:25:51 -0800 (PST) Received: from mailsrv14.zmi.at (mailsrv1.zmi.at [212.69.164.54]) by cuda.sgi.com with ESMTP id O7HeoFlje3aemEv0 for ; Mon, 10 Jan 2011 05:25:51 -0800 (PST) From: Michael Monnerie Subject: Re: [PATCH] xfs_repair: multithread phase 2 Date: Mon, 10 Jan 2011 14:25:47 +0100 References: <1294620248-17098-1-git-send-email-david@fromorbit.com> <201101100857.53421@zmi.at> <20110110084122.GF28803@dastard> In-Reply-To: <20110110084122.GF28803@dastard> MIME-Version: 1.0 Message-Id: <201101101425.48134@zmi.at> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============3542928119913523708==" Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: xfs@oss.sgi.com --===============3542928119913523708== Content-Type: multipart/signed; boundary="nextPart1650099.Et3F0g51rS"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit --nextPart1650099.Et3F0g51rS Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable On Montag, 10. Januar 2011 Dave Chinner wrote: > Pretty much > every sata disk supports NCQ these days, and default to a depth of > 32, which means we can have 32 concurrent reads in progress at once. > Phase 2 is all synchronous IO, so the only way to hide the IO > latency is to queue work to multiple threads and switch between the > threadsto work on another queue when the current one blocks waiting > for IO. This is interesting. Did you measure this with a rotating single disk?=20 Is the idle time between two synchronous reads bigger than the time=20 needed to move the disk head to another cylinder and read a sector? That=20 takes ~15ms on a normal disk, incredibly long compared to cpu speed.=20 Even with NCQ, the disk would have to swing the head a lot, and just=20 from thinking about it I wouldn't believe that it's faster like this. But I'm sure you tested it so I take it as given that it's like that.=20 Cool improvement, btw :-) =2D-=20 mit freundlichen Gr=FCssen, Michael Monnerie, Ing. BSc it-management Internet Services: Prot=E9ger http://proteger.at [gesprochen: Prot-e-schee] Tel: +43 660 / 415 6531 // ****** Radiointerview zum Thema Spam ****** // http://www.it-podcast.at/archiv.html#podcast-100716 //=20 // Haus zu verkaufen: http://zmi.at/langegg/ --nextPart1650099.Et3F0g51rS Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.15 (GNU/Linux) iEYEABECAAYFAk0rCNwACgkQzhSR9xwSCbSyCACdHz+28KANhrkKs8oS88W5NstK Kv0AmgJmVOsY12MjCcTv1vdalkJ3G8cU =WhJO -----END PGP SIGNATURE----- --nextPart1650099.Et3F0g51rS-- --===============3542928119913523708== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs --===============3542928119913523708==--