Fwd: Tomcat6 port keeps locking up??

[Steven Hartland]

----- Original Message ----- 
From: "Jeremy Chadwick"
> On Fri, Sep 17, 2010 at 12:19:00PM +0300, Andriy Gapon wrote:
>> on 17/09/2010 11:56 Jeremy Chadwick said the following:
>> > I don't think you understand how Solaris's VM behaves with ZFS.  It
>> > behaves very differently than FreeBSD.  On Solaris/OpenSolaris with ZFS,
>> > you'll see the ARC taking up as much memory as possible -- but unlike
>> > FreeBSD (AFAIK), when a userland or kernel application requires more
>> ^^^^^^^^^^^^^^^^^
>> > memory, the Solaris kernel dynamically releases portions of the ARC.
>> 
>> Can you please explain that "unlike" part?
> 
> When ZFS was first introduced to FreeBSD, I was given the impression
> from continual posts on the mailing lists that memory which was
> allocated to the ARC was never released in the situation that a userland
> program wanted memory.
> 
> An example scenario.  These numbers are in no way accurate given many
> other things (network mbufs, UFS and VFS cache, etc.):
> 
> - amd64 system has 2GB physical RAM (assume ~1920MB usable)
> - vm.kmem_size="1536M" + vfs.zfs.arc_max="1400M"
> - Heavy ZFS I/O results in ARC maxing out at ~1400MB
> - Userland application runs, requests malloc() of 1024MB
> - Userland gets 384MB from physical RAM, remaining 640MB from swap
> - ARC remains at 1400MB
> 
> Is this no longer the case?

My experience is no this is no longer the case at least on stable + patches
mentioned on thread:-
"zfs very poor performance compared to ufs due to lack of cache?"

    Regards
    Steve

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