varnishd: out of swap space (was: Varnishd 1.1.2 returns 5xx)

[Lin Jui-Nan Eric]

Now I encounter another problem: out of swap space.
> dmesg -a | tail -10
swap_pager_getswapspace(6): failed
swap_pager_getswapspace(4): failed
swap_pager_getswapspace(8): failed
swap_pager_getswapspace(8): failed
swap_pager_getswapspace(8): failed
swap_pager_getswapspace(9): failed
swap_pager_getswapspace(8): failed
swap_pager_getswapspace(8): failed
pid 4190 (varnishd), uid 65534, was killed: out of swap space
Dec 23 07:47:39 rproxy2 kernel: pid 4190 (varnishd), uid 65534, was
killed: out of swap space
> uname -a
rproxy2 [/net/account/admin/jnlin] -jnlin- uname -a
FreeBSD rproxy2 7.0-BETA2 FreeBSD 7.0-BETA2 #1: Mon Nov 12 16:06:40
CST 2007     root at rproxy2:/usr/obj/usr/src/sys/KERNEL  amd64
> cat /var/run/dmesg.boot | head -22
Copyright (c) 1992-2007 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
FreeBSD is a registered trademark of The FreeBSD Foundation.
FreeBSD 7.0-BETA2 #1: Mon Nov 12 16:06:40 CST 2007
    root at rproxy2:/usr/obj/usr/src/sys/KERNEL
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Genuine Intel(R) CPU                  @ 2.66GHz (2660.01-MHz K8-class CPU)
  Origin = "GenuineIntel"  Id = 0x6f4  Stepping = 4
  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>
  Features2=0x4e3bd<SSE3,RSVD2,MON,DS_CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,DCA>
  AMD Features=0x20100800<SYSCALL,NX,LM>
  AMD Features2=0x1<LAHF>
  Cores per package: 2
usable memory = 4285853696 (4087 MB)
avail memory  = 4124594176 (3933 MB)
ACPI APIC Table: <PTLTD          APIC  >
FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
 cpu0 (BSP): APIC ID:  0
 cpu1 (AP): APIC ID:  1
 cpu2 (AP): APIC ID:  6
 cpu3 (AP): APIC ID:  7

Do I need to tune any sysctl values or...?
Thank you for any suggestions!