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Date:      Wed, 27 Aug 2003 13:59:42 +0200 (SAST)
From:      Irvine Short <irvine@sanbi.ac.za>
To:        freebsd-questions@freebsd.org
Subject:   Large memory issues
Message-ID:  <20030827133322.X83260@fling.sanbi.ac.za>

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Hey All

I'm running 4-STABLE as of about a week ago.

The machine is a dual 2.4GHz Xeon with hyperthreading enabled and 4GB RAM.

The box has been running fine for a few months now, being used as a number
cruncher.

Yesterday one of the users noticed that he was limited to 512MB RAM per
process.

I poked around in LINT and found this:
options         MAXDSIZ="(256*1024*1024)"
options         MAXSSIZ="(256*1024*1024)"
options         DFLDSIZ="(256*1024*1024)"

for max data size, max stack size, and default data size.

I put this in my kernel config file:
options         MAXDSIZ="(4096*1024*1024)"
options         MAXSSIZ="(64*1024*1024)"
options         DFLDSIZ="(512*1024*1024)"

I then rebooted and the box got nowhere with sh exiting on a signal 11

I then tried:
options         MAXDSIZ="(4095*1024*1024)"
options         MAXSSIZ="(64*1024*1024)"
options         DFLDSIZ="(512*1024*1024)"

and it was slightly better - managed to boot halfway with everything
running out of memory.

I then found that this:
options         MAXDSIZ="(2048*1024*1024)"
options         MAXSSIZ="(128*1024*1024)" (and also 64MB)
options         DFLDSIZ="(512*1024*1024)"

worked fine but not as expected - limit reports datasize unlimited.

I'd kind of like a default of 512MB with the option to loosen it.

Any offers as to what's the proper way to do this? All's well at the mo
but it doesn't seem right.

Configging MAXDSIZ to 3500*1024*1024 did the same as 4095

Also, when the machine boots it says:
CPU: Intel(R) Xeon(TM) CPU 2.40GHz (2392.25-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0xf27  Stepping = 7

Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS
,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Hyperthreading: 2 logical CPUs
real memory  = 4025942016 (3931584K bytes)

and then later it says on the console something like:
256MB of RAM over 4GB ignored.

Seems silly to waste 256MB RAM so any hints would be appreciated here
too.

Cheers,


Irvine Short

Sys Admin
SANBI, University of the Western Cape, South Africa
http://www.sanbi.ac.za
tel: +27-21-959 3645
cel: +27-82-494 3828



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