From: malahal@us.ibm.com
To: dm-devel@redhat.com
Subject: Re: multipath multibus performance
Date: Thu, 31 Jan 2008 10:26:47 -0800 [thread overview]
Message-ID: <20080131182647.GA27979@us.ibm.com> (raw)
In-Reply-To: <20080131163918.GA10313@thumper2>
Andy [genanr@emsphone.com] wrote:
> I would like to increase the performance of the multibus mode of multipath.
> It would be nice if multibus performance would be very close to accessing
> the device directly. From what I have been told, under multibus, I/O's are
> broken up into bio's and sent down the multiple paths, with no merging of
> adjacent I/O's.
Not quite correct. It depends on the path selector algorithm you use.
"round_robin" with rr_min_io set to 1 will definitely give you bad
performance for sequential I/O. If you set rr_min_io to a big number,
the adjacent I/Os may be merged together. What values did you use in
your testing?
--Malahal.
prev parent reply other threads:[~2008-01-31 18:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-31 16:39 multipath multibus performance Andy
2008-01-31 18:26 ` malahal [this message]
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