Date: Fri, 17 Sep 2010 12:53:09 +0300 From: Andriy Gapon <avg@icyb.net.ua> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-ports@freebsd.org Subject: Re: Fwd: Tomcat6 port keeps locking up?? Message-ID: <4C933A85.8080703@icyb.net.ua> In-Reply-To: <20100917094212.GA49319@icarus.home.lan> References: <4C926418.2050407@gmail.com> <4C9328B9.4010100@gmail.com> <20100917085621.GA48570@icarus.home.lan> <4C933284.6050601@icyb.net.ua> <20100917094212.GA49319@icarus.home.lan>
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on 17/09/2010 12:42 Jeremy Chadwick said the following: > 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? > I am not sure if this has even been the case :-) It is definitely not the case now. -- Andriy Gapon
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