From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH] [RFC] multipath: change the DEFAULT_MINIO for the request based multipath Date: Thu, 20 Jan 2011 08:32:35 +0100 Message-ID: <4D37E513.3070506@suse.de> References: <91d6dae7d88296d8a1fe.1295472607@malahal> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <91d6dae7d88296d8a1fe.1295472607@malahal> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development List-Id: dm-devel.ids On 01/19/2011 10:30 PM, Malahal Naineni wrote: > The value of 1000 is good for bio based multipath. Seen 50% increase in > I/O ops by setting it to 1 in request based multipath configuration. > This patch would give poor performance for people still using the bio > based multipath! > = > Is it possible to detect request based multipath and change only for > those configurations? > = > diff -r e504a50b0db5 -r 91d6dae7d882 libmultipath/defaults.h > --- a/libmultipath/defaults.h Wed Jan 19 13:16:40 2011 -0800 > +++ b/libmultipath/defaults.h Wed Jan 19 13:29:52 2011 -0800 > @@ -5,7 +5,7 @@ > #define DEFAULT_ALIAS_PREFIX "mpath" > #define DEFAULT_FEATURES "0" > #define DEFAULT_HWHANDLER "0" > -#define DEFAULT_MINIO 1000 > +#define DEFAULT_MINIO 1 > #define DEFAULT_PGPOLICY FAILOVER > #define DEFAULT_FAILBACK -FAILBACK_MANUAL > #define DEFAULT_RR_WEIGHT RR_WEIGHT_NONE > = Heh, that was the main reason for using request-based multipathing :-) So yes, changing the behaviour is a good idea. But we should equally be able to detect if request-based multipathing is present; maybe we can key off the version number of dm-multipath? Cheers, Hannes -- = Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: Markus Rex, HRB 16746 (AG N=FCrnberg)