Re: new ZFS sysctls not working?

On Mon, Apr 09, 2007 at 10:07:12PM -0500, Doug Poland wrote:
> On Mon, Apr 09, 2007 at 10:58:55PM -0400, Kris Kennaway wrote:
> > On Mon, Apr 09, 2007 at 09:50:20PM -0500, Doug Poland wrote:
> > > On Mon, Apr 09, 2007 at 09:05:32PM -0400, Kris Kennaway wrote:
> > > > On Mon, Apr 09, 2007 at 06:26:54PM -0500, Doug Poland wrote:
> > > > > Hello,
> > > > > 
> > > > > It would appear that the new sysctls for ZFS
> > > > > (vfs.zfs.arc_max/min) are not "taking".  i.e.,
> > > > > 
> > > > > # cat /boot/loader.conf
> > > > > vfs.zfs.arc_max=134217728
> > > > > vfs.zfs.arc_min=134217728
> > > > > 
> > > > > # sysctl -a | grep vfs.zfs.arc
> > > > > vfs.zfs.arc_max: 67108864
> > > > > vfs.zfs.arc_min: 67108864
> > > > > 
> > > > > This is after a fresh cvsup run today around 10:00 CDT.
> > > > 
> > > > Please provide more details of your system, e.g. sysctl
> > > > vm.kmem_size.
> > > > 
> > > FreeBSD 7.0-CURRENT #0: Mon Apr  9 12:55:54 CDT 2007
> > >     djp_at_seth.polands.org:/usr/obj/usr/src/sys/GENERIC
> > > WARNING: WITNESS option enabled, expect reduced performance.
> > > Timecounter "i8254" frequency 1193182 Hz quality 0
> > > CPU: AMD Athlon(tm) processor (1403.19-MHz 686-class CPU)
> > >   Origin = "AuthenticAMD"  Id = 0x644  Stepping = 4
> > >   Features=0x183f9ff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FXSR>
> > >   AMD Features=0xc0440800<SYSCALL,<b18>,MMX+,3DNow!+,3DNow!>
> > > real memory  = 259981312 (247 MB)
> > > avail memory = 240451584 (229 MB)
> > > 
> > > # sysctl -a | grep vm.kmem_size
> > > vm.kmem_size: 80662528
> > > vm.kmem_size_max: 335544320
> > > vm.kmem_size_scale: 3
> > 
> > Yeah, you don't even have 128 MB of kmem available (only 76 MB), so
> > it's no surprise zfs refused to use that much ;-)
> > 
> I was attempting to "portsnap extract" to a two disk ZFS mirror.  It
> would appear my ability to test ZFS is severly limited on this
> particular hardware configuration.  Sorry for the noise...

Well you can increase your kmem a bit, but yeah, it's probably not
going to perform very well because you're taking it away from userland
so there will be increased swap activity too.

Kris