Subject: Re: UVM/other problems for desktop users in current?
To: John Franklin <franklin@elfie.org>
From: Gary Thorpe <gathorpe79@yahoo.com>
List: current-users
Date: 12/20/2002 09:27:43
 --- John Franklin <franklin@elfie.org> wrote: > On Thu, Dec 19, 2002
at 10:50:53PM +0200, Jukka Marin wrote:
> > On Wed, Dec 18, 2002 at 10:14:27AM -0500, John Franklin wrote:
> > > > The poor machine can't even handle one CVS operation without
> failing to
> > > > serve files over NFS.  CPU usage on the server is less than 20%
> and
> > > > there's over 300 MB of RAM available.
> > > 
> > > options BUFCACHE <30-50> on the server will clean that up. 
> BUFCACHE, if
> > > unmodified, is 5% of your memory.  It's used for both NFS network
> > > buffers and fs metadata buffers.  For NFS servers 5% is grossly
> > > inadequate.  Watch systat bufcache (NFS buffers are charged to
> the root fs.)
> > 
> > Sure enough, 99% of buffers were allocated by root.  But, after
> setting
> > 
> > options        BUFCACHE=30
> > 
> > I could no longer boot:
> > 
> > cpu0: AMD Athlon Model 4 (Thunderbird) (686-class), 700.10 MHz
> > cpu0: I-cache 64 KB 64b/line 2-way, D-cache 64 KB 64b/line 2-way
> > cpu0: L2 cache 256 KB 64b/line 16-way
> > cpu0: features 183f9ff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,MTRR>
> > cpu0: features 183f9ff<PGE,MCA,CMOV,FGPAT,PSE36,MMX>
> > cpu0: features 183f9ff<FXSR>
> > total memory = 511 MB
> > panic: cpu_startup: cannot allocate VM for buffers
> >
> > So, _how_ do I make it allocate more buffers when BUFCACHE=30
> causes a
> > panic?
>  
> Weird.  Ok.  The BUFCACHE option represents the percentage of memory
> to
> allocate to BUFCACHE.  30% of 511M is 153M.  I seem to have mine set
> to
> 25 (.25 * 446M = 111M).  I wonder if it can't handle more than 128M
> of
> buffers.  Try cutting it down to 25 (127.75M) and see if you can
> boot.
> 
> Also, what kernel version are you running?  My dmesg is in a
> different
> order: 
> 
> NetBSD 1.6K (DM.MP) #0: Sun Dec  8 05:35:41 EST 2002
>     franklin@deathmitten:/usr/src2/sys/arch/i386/compile/DM.MP
> total memory = 447 MB
> avail memory = 323 MB
> using 6144 buffers containing 111 MB of memory
> BIOS32 rev. 0 found at 0xfb290
> mainbus0 (root)
> mainbus0: Intel MP Specification (Version 1.1) (OEM00000
> PROD00000000)
> cpu0 at mainbus0: apid 0 (boot processor)
> cpu0: Intel Pentium II (Klamath) (686-class), 267.30 MHz, id 0x633
> cpu0: features
> 80fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR>
> cpu0: features 80fbff<PGE,MCA,CMOV,MMX>
> 
> jf
> -- 
> John Franklin
> franklin@elfie.org
> ICBM: 3543'56"N 7853'27"W

So what exaqctly is the point of UBC if you have to manually configure
how much buffer cache your system will use? Is file system I/O and
device buffering now unified, but not much else (and was this this case
before anyway)? How is this different from the compile-time setting
used in 1.5?



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