Date: Sat, 14 Jan 2006 13:09:02 -0500 From: David Miller <dmiller@sparks.net> To: Arne Woerner <arne_woerner@yahoo.com> Cc: freebsd-database@freebsd.org, freebsd-performance@freebsd.org Subject: Re: Horrible PostgreSQL performance with NFS Message-ID: <43C93E3E.30009@sparks.net> In-Reply-To: <20060114144202.6199.qmail@web30315.mail.mud.yahoo.com> References: <20060114144202.6199.qmail@web30315.mail.mud.yahoo.com>
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Arne Woerner wrote: >--- Slawek Zak <slawek.zak@gmail.com> wrote: > > >>On 1/13/06, Arne Woerner <arne_woerner@yahoo.com> wrote: >>40MB/s. CPU load negligible. I don't have >>an exact number, as this machine has other >>processes running. But overall, the system >>load didn't exceed 5%. >> >> >> >Looks good... > > > >>I saturated fast ethernet on the host >>with this test. Filer is connected with >>Gb and can spew around 70MB/s easily. >>CPU load on the host didn't exceed 4%. >> >> >> >Looks even better... :-) > > > >>>3. test the NIC performance with >>> >>> >>Filer doesn't respond to large icmp packets. >> >> >> >Ok... This isn't so important, since NFS speed is higher than >local disc speed. > > > >>>My theory would be, that your NICs need a >>>lot of CPU time, while your local discs >>>dont need so much CPU time. :-) >>> >>> >>I don't think so. Drivers account for system >>time. It doesn't exceed 20% of overall load. >>The postgres processes are very busy doing >>almost nothing. Semops is most of the work >>they seem to do. >> >> >> >Hmm... > >But why does switching from local disc to NFS makes the PostgreSQL >performance so bad? > > It certainly sounds like something is no longer caching things - either reads or writes or both - when using NFS. Does FreeBSD 6.x have a version of lockd that works with the netApp? --- David
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