Re: 2.6.4-mm2

From: Chris Mason
Date: Thu Mar 18 2004 - 14:09:25 EST


On Thu, 2004-03-18 at 13:48, markw@xxxxxxxx wrote:
> On 18 Mar, Andrew Morton wrote:
> > markw@xxxxxxxx wrote:
> >>
> >> Sorry I'm falling behind... I see about a 10% decrease in throughput
> >> with our dbt2 workload when comparing 2.6.4-mm2 to 2.6.3. I'm wondering
> >> if this might be a result of the changes to the pagecache, radix-tree
> >> and writeback code since you mentioned it could affect i/o scheduling in
> >> 2.6.4-mm1.
> >
> > Could be. Have you run tests without LVM in the picture?
>
> No I haven't and I'm hesitant to. I have 52 single drives in one volume
> and 14 single drives the other. Because it's PostgreSQL, my options are
> to either run on a single drive (and not be able to drive the system as
> hard) or to reconfigure my drives using hardware raid. I could do the
> latter if you think it'll help. It's just a bit time consuming.
>
It might be more valuable to retest on 2.6.5-rc1-mm2. I'm assuming
postgres was doing synchronous writes, and 2.6.4-mm2 doesn't really wait
correctly.

-chris


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