Date: Fri, 17 Sep 2010 02:42:12 -0700 From: Jeremy Chadwick <freebsd@jdc.parodius.com> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-ports@freebsd.org Subject: Re: Fwd: Tomcat6 port keeps locking up?? Message-ID: <20100917094212.GA49319@icarus.home.lan> In-Reply-To: <4C933284.6050601@icyb.net.ua> References: <4C926418.2050407@gmail.com> <4C9328B9.4010100@gmail.com> <20100917085621.GA48570@icarus.home.lan> <4C933284.6050601@icyb.net.ua>
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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? -- | Jeremy Chadwick jdc@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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