Message-ID: <434BDA1E.5030804@rentec.com>
Date: Tue, 11 Oct 2005 11:28:30 -0400
From: Alan Stange <stange@rentec.com>
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To: Alex Turner <armtuk@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Performance on SUSE w/ reiserfs
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Alex Turner wrote:

> Perhaps this is true for 1.5 on x86-32 (I've only used it on x86-64) 
> but I was more thinking 1.4 which many folks are still using.

The 1.4.x JVM's will also work just fine with much more than 1GB of 
memory.   Perhaps you'd like to try again?

-- Alan

>
> On 10/11/05, *Alan Stange* <stange@rentec.com 
> <mailto:stange@rentec.com>> wrote:
>
>     Alex Turner wrote:
>
>     > Realise also that unless you are running the 1.5 x86-64 build, java
>     > will not use more than 1Gig, and if the app server requests more
>     than
>     > 1gig, Java will die (I've been there) with an out of memory error,
>     > even though there is plenty of free mem available.  This can
>     easily be
>     > cause by a lazy GC thread if the applicaiton is running high on
>     CPU usage.
>
>     On my side of Planet Earth, the standard non-x64 1.5 JVM will happily
>     use more than 1G of memory (on linux and Solaris, can't speak for
>     Windows).  If you're running larger programs, it's probably a good
>     idea
>     to use the -server compiler in the JVM as well.  I regularly run with
>     -Xmx1800m and regularly have >1GB heap sizes.
>
>     The standard GC will not cause on OOM error if space remains for the
>     requested object.  The GC thread blocks all other threads during its
>     activity, whatever else is happening on the machine.   The
>     newer/experimental GC's did have some potential race conditions, but I
>     believe those have been resolved in the 1.5 JVMs.
>
>     Finally, note that the latest _05 release of the 1.5 JVM also now
>     supports large page sizes on Linux and Windows:
>     -XX:+UseLargePages   this can be quite beneficial depending on the
>     memory patterns in your programs.
>
>     -- Alan
>
>