From mboxrd@z Thu Jan 1 00:00:00 1970 From: Justin Piszcz Subject: Re: stripe_cache_size and performance Date: Fri, 22 Jun 2007 11:10:45 -0400 (EDT) Message-ID: References: <5d96567b0706211242p7f03bd1cw9102ae3e44d67cee@mail.gmail.com> <5d96567b0706220801v76c1c19cl7448050e62e0860b@mail.gmail.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Return-path: In-Reply-To: <5d96567b0706220801v76c1c19cl7448050e62e0860b@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: Raz Cc: jnelson-linux-raid@jamponi.net, linux-raid@vger.kernel.org List-Id: linux-raid.ids I have found a 16MB stripe_cache_size results in optimal performance after testing many many values :) On Fri, 22 Jun 2007, Raz wrote: > On 6/22/07, Jon Nelson wrote: >> On Thu, 21 Jun 2007, Raz wrote: >> >> > What is your raid configuration ? >> > Please note that the stripe_cache_size is acting as a bottle neck in some >> > cases. >> >> Well, it's 3x SATA drives in raid5. 320G drives each, and I'm using a >> 314G partition from each disk (the rest of the space is quiescent). > what is the chunk size ?. Please note that a raid performance is dependent > on the access pattern to the disks. What is this raid aimed to do ? > more reads ? more writes ? If you can control the access pattern , > you might be able to increase performance. >> > On 6/21/07, Jon Nelson wrote: >> > > >> > > I've been futzing with stripe_cache_size on a 3x component raid5, >> > > using 2.6.18.8-0.3-default on x86_64 (openSUSE 10.2). >> > > >> > > With the value set at 4096 I get pretty great write numbers. >> > > 2048 and on down the write numbers slowly drop. >> > > >> > > However, at values above 512 the 'check' performance is terrible. By >> > > 'check' performance I mean the value displayed by /proc/mdstat after >> > > I issue: >> > > >> > > echo check > /sys/block/md0/md/sync_action >> > > >> > > When I say "terrible" I mean < 3MB/s. >> > > When I use 384, the performance goes to ~70MB/s >> > > 512.. 72-73MB/s >> > > 640.. 73-74MB/s >> > > >> > > 768.. 3300 K/s. Wow! >> > > >> > > Can somebody 'splain to me what is going on? >> > > >> > > -- >> > > Jon Nelson >> > > - >> > > To unsubscribe from this list: send the line "unsubscribe linux-raid" >> in >> > > the body of a message to majordomo@vger.kernel.org >> > > More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > >> > >> > >> > -- >> > Raz >> > >> > >> > >> >> -- >> Jon Nelson >> - >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > > -- > Raz > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >