9.1 minimal ram requirements

[Ian Smith]

On Sun, 23 Dec 2012 03:45:39 +0300, Sergey Kandaurov wrote:
 > On 23 December 2012 03:40, Marten Vijn <info at martenvijn.nl> wrote:
 > > On 12/23/2012 12:27 AM, Jakub Lach wrote:
 > >>
 > >> Guys, I've heard about some absurd RAM requirements
 > >> for 9.1, has anybody tested it?
 > >>
 > >> e.g.
 > >>
 > >> http://forums.freebsd.org/showthread.php?t=36314
 > >
 > >
 > > jup, I can comfirm this with nanobsd (cross) compiled
 > > for my soekris net4501 which has 64 MB mem:
 > >
 > > from dmesg: real memory  = 67108864 (64 MB)
 > >
 > > while the same config compiled against a 9.0 tree still works...

Same as the first message in that forum thread, I tried installing from 
i386 9.1-RC3 memstick on a PIII-M with 128MB RAM (Thinkpad T23) and it 
panics just a few percent into extracting base.txz, much to my surprise.

I had a 256MB stick and was going to try that instead, but was in a bit 
of a hurry so just added it for 384MB and have had no further trouble, 
but haven't done anything much with it yet, no X or other packages.

However the same forum user 'Zav' later reports the same panic at 2.5d 
uptime with 320MB, after earlier panics with 192MB post-installation 
when 'trying to do something', so I'm wondering if even 256MB is enough 
for 9.1? .. scratch my ambition to upgrade an older maxed-out 160MB 
laptop that runs fine on 5.5 w/X, KDE and all, albeit using some swap.

 > This (i.e. the "kmem_map too small" message seen with kernel memory
 > shortage) could be due to CAM CTL ('device ctl' added in 9.1), which is
 > quite a big kernel memory consumer.
 > Try to disable CTL in loader with kern.cam.ctl.disable=1 to finish boot.

I've just added that, thanks Sergey, but it's sadly not an option for 
installation.  I guess it's too late for the release notes - which at 
RC3 made no mention of CAM CTL at all - but it's not yet clear to me 
whether even 256MB is enough to boot, install and run 9.1 GENERIC?

 > A longer term workaround could be to postpone those memory allocations
 > until the first call to CTL.

Under what circumstances is CAM CTL needed?  What would leaving it out 
of GENERIC cost, and whom?  Is it loadable?  dmesg.boot reports loading, 
but I don't see a module, nor can I find much information about CTL in 
cam(3|4) or /sys/conf/NOTES.  apropos found ctladm and ctlstat, but I'm 
little the wiser as to when it may be needed, beyond CAM/SCSI debugging?

 > # cam ctl init allocates roughly 35 MB of kernel memory at once
 > # three memory pools, somewhat under M_DEVBUF, and memory disk
 > # devbuf takes 1022K with kern.cam.ctl.disable=1
 > 
 >          Type InUse MemUse HighUse Requests  Size(s)
 >        devbuf   213 20366K       -      265  16,32,64,128,256,512,1024,2048,4096
 >        ctlmem  5062 10113K       -     5062  64,2048
 >        ctlblk   200   800K       -      200  4096
 >       ramdisk     1  4096K       -        1
 >       ctlpool   532   138K       -      532  16,512
 > 
 > -- 
 > wbr,
 > pluknet

cheers, Ian