From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: some general questions on RAID Date: Mon, 8 Jul 2013 14:53:16 +1000 Message-ID: <20130708145316.4486d0dc@notabene.brown> References: <1372962602.8716.56.camel@heisenberg.scientia.net> <51D5F22C.70007@turmel.org> <51D9A7CF.6000700@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/hsFSdkRgVA5ip1+T2kxYfjm"; protocol="application/pgp-signature" Return-path: In-Reply-To: <51D9A7CF.6000700@gmail.com> Sender: linux-raid-owner@vger.kernel.org To: Milan Broz Cc: Phil Turmel , Christoph Anton Mitterer , linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/hsFSdkRgVA5ip1+T2kxYfjm Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Sun, 07 Jul 2013 19:39:27 +0200 Milan Broz wrote: > So if you have multiple IOs submitted in parallel from *different* CPUs, > they are processed in parallel. >=20 > If you have MD over dmcrypt, this can cause problem that MD sumbits all I= Os > with the same cpu context and dmcrypt cannot run it in parallel. For RAID1 and RAID10 this isn't true any more. Commit f54a9d0e59c4bea3db733921ca9147612a6f292c in 3.6 changed this for RAID1 and a similar commit did for RAID10. RAID4/5/6 still submit from a single thread as you say. NeilBrown --Sig_/hsFSdkRgVA5ip1+T2kxYfjm Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIVAwUBUdpFvDnsnt1WYoG5AQJn9RAArL1Oi1qgoFJOlx4lpktsD77VW5JWQh8T 5/H7u0cxcyl8Khcpcacor1xpjaaFoDB+ngpD28g1zx5AJpGEoD99/+WW8LyQUJzr 3apnxxJsrbZkoj26tueZ/mw1iMc0GupJqu+GIWvHSMkbwDxDa/j6kT45eRDNg0Cr 9WlpEj8QfIvrTiWztE5A+4aXCOSWq3qbW263bOfH11rHqiWrI+8HdHZZ+W8PLt8I AFSkbwTJQkzHir2SerMifXTiTxOjDWnpwhAIauubDGMEjCxZZbtS7V3WEubgt+Z+ a2s7o6eyBhapp8zpvUPGM71viQZws+5j7Uce6bbVrW7dZjU2P73NPrGlJ2iuvJlb c2AYQOIKNEtBVc3WE68pyf4S6T4NXk92TncvFLp5xMC51IPsqKxp9lVvFmvxKA52 ItdFYUhBb7WejDm9a9eC14CaCHvh2Clsx14RQ9txhJSlqWbTCJZUlbFG3veMikgG rsD/hd8L/oddCUHJMHQAYPWIw0VLKhoCm+tb0u1ipjCs6i1CrXYRHl3ywIiBM2qk d24pm/lMCQ2WJpscU145GhJmFhAY92NcGs+KyerpxeMjpQpP/ANVWTH29oP1DOIv zwUqivvUHWNBG85CE2c9nl3p+dE0sicTGt7Uj5r6b9x3gpxpwlPq5IOkXh+4OYOJ i4GUakdTpL4= =U2Fh -----END PGP SIGNATURE----- --Sig_/hsFSdkRgVA5ip1+T2kxYfjm--