[mrtg] Re: Performance Problem

Wed Feb 23 22:54:38 MET 2005

Chuck,
    I don't know the feasibility of this suggestion, but you may wish to
consider moving to either FreeBSD 4.11 or FreeBSD 5.3  .

FreeBSD 5.1 has lots (LOTS) of debug stuff turned on by default as it is
considered a pre-production release.  I think you would have better
performance without much tuning if you were to migrate to FBSD 4.11 -
(highly evolved production release) or FBSD 5.3 - (the first production
release in the 5.0 family).

I would try that first before trying to tune FBSD 5.1

Best, Jon

----- Original Message ----- 
From: <Chuck.Coker>
Sent: Wednesday, February 23, 2005 3:48 PM
Subject: [mrtg] Performance Problem

: Hi Folks,
:
: We are having major performance problems with our MRTG box. We are
: currently monitoring 507 routers and switches with 9,621 interfaces.
: I probably have another 200-300 routers and switches to add. That's not
: too many is it?
:
: When polling these devices at five minute intervals, I run out of swap
: space and receive this error message:
:     swap_pager_getswapspace: failed
:
: So far, I've increased the polling interval from five minutes to ten
: minutes and it has temporarily solved the swap space problems. We get
: the occasional gray bar (as in no response) in our graphs, but overall
: things are working reasonably well.
:
: When I try to add any more devices, I start getting the swap space
: errors again. I suspect that I've reached the limits of what our little
: MRTG box can do.
:
: It appears that we have plenty of unused memory, so the bottleneck
: should be with something else, for example, running out of buffers. On
: the FreeBSD web site, they suggest increasing the kern.ipc.nmbclusters
: to somewhere between 1024 to 4096. Right now we have it set to 8960.
: Could we have it set too high?
:
: I'm wondering if there is anything that we can tweak to get better
: performance. The box only runs MRTG and Apache, so anything I need to do
: to make MRTG work better at the expense of something else is okay.
:
: I've included some of the info from netstat, sysctl, and dmesg. We also
: have kern.ipc.numopensockets set to 10 and kern.ipc.maxsockets set to
: 4008.
:
: Thanks,
: Chuck
:
: PS: Does anyone know of a place where I can find descriptions what all
: the sysctl variables are used for? I mean more of a description than the
: output from:
:     sysctl -d -a
: I'm looking for enough information to make educated guesses about what
: can be tweaked and by how much or how little.
:
: ======================================================================
:
: $ netstat -m
: mbuf usage:
: GEN cache: 0/0 (in use/in pool)
: CPU #0 cache: 129/192 (in use/in pool)
: Total: 129/192 (in use/in pool)
: Mbuf cache high watermark: 512
: Maximum possible: 17920
: Allocated mbuf types:
:   129 mbufs allocated to data
: 1% of mbuf map consumed
: mbuf cluster usage:
: GEN cache: 0/0 (in use/in pool)
: CPU #0 cache: 128/152 (in use/in pool)
: Total: 128/152 (in use/in pool)
: Cluster cache high watermark: 128
: Maximum possible: 8960
: 1% of cluster map consumed
: 352 KBytes of wired memory reserved (81% in use)
: 0 requests for memory denied
: 0 requests for memory delayed
: 0 calls to protocol drain routines
:
: ======================================================================
:
: $ sysctl -A | grep mbuf
: kern.ipc.nmbufs: 17920
: kern.ipc.mbuf_wait: 64
: kern.ipc.mbuf_hiwm: 512
: kern.ipc.mbuf_lowm: 128
:       mbufmgr    32    79K     79K      459
: 16,32,64,256,4096,8192,65536
:
: ======================================================================
:
: $ dmesg
: ...
: FreeBSD 5.1-RELEASE #0: Thu Jun  5 02:55:42 GMT 2003
:     root at wv1u.btc.adaptec.com:/usr/obj/usr/src/sys/GENERIC
: Preloaded elf kernel "/boot/kernel/kernel" at 0xc06d4000.
: Preloaded elf module "/boot/kernel/acpi.ko" at 0xc06d421c.
: Timecounter "i8254"  frequency 1193182 Hz
: Timecounter "TSC"  frequency 730949743 Hz
: CPU: Intel Pentium III (730.95-MHz 686-class CPU)
:     Origin = "GenuineIntel"  Id = 0x683  Stepping = 3
:
: Features=0x383fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,
: MCA,CMOV,PAT,PSE36,MMX,FXSR,SSE>
: real memory  = 268304384 (255 MB)
: avail memory = 253231104 (241 MB)
: ...
:
: ----------------------------------------------------------------
: Chuck Coker                             chuck.coker (et) rcc.edu
:        Riverside Community College, Information Services
: 4800 Magnolia Avenue, Riverside, California 92506, United States
: +1 951 222 8759 (desk)                    +1 951 830 8068 (cell)
: ----------------------------------------------------------------
:
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