Date: Tue, 23 Apr 2002 16:53:16 -0600 From: "Jan L. Peterson" <jlp@softhome.net> To: freebsd-questions@freebsd.org Subject: looking for magic knob to twiddle Message-ID: <20020423225317.F3F9241F22@mail.flipdog.com>
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Hi, all.
I've been pouring through the archives, but have not found the magic
knob I need to twiddle.
I have a box that is being pressed into service as a high-volume Samba
file server.
Specifics: the box is an HP LC 2000, currently with 1G of RAM, and an
HP Netraid 3si card (same as an AMI MegaRaid, uses the amr driver).
I've got a stack of disk configured as a RAID 5 array (6x 36G drives).
Looking at top, I see memory usage broken down like this:
Mem: 55M Active, 756M Inact, 143M Wired, 49M Cache, 112M Buf, 1964K Free
Now, maybe I'm reading that wrong, but it looks to me like only 112M of
the 1G of RAM is being used as filesystem buffer. Due to the usage
pattern of this machine, I end up with a whole stack of smbd processes
sitting in biord state, waiting for a read to be satisfied.
Yesterday, when I only had 512M of RAM in the box, I was getting 61M of
Buf reported by top.
Here is a sampling of iostat output:
tty amrd0 amrd1 amrd2 cpu
tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id
0 301 16.00 0 0.00 11.11 137 1.48 0.00 0 0.00 7 0 9 2 81
0 551 0.00 0 0.00 10.36 100 1.01 0.00 0 0.00 5 0 7 1 88
0 658 0.00 0 0.00 10.39 120 1.22 0.00 0 0.00 4 0 5 1 90
Observe that amrd1 is getting about 1.25MB/s of throughput.
If I reduce the smbd load on the machine (by stopping a bunch of the
clients), that number climbs to 5+MB/s. Unfortunately, I need to have
all of the clients running.
Relevant system information: 4.5-RELEASE, custom kernel (I can show
you the kernel config, dmesg output, loader.conf, and sysctl.conf if
you like).
I know that the netraid card is capable of doing better than the
1.25MB/s (indeed, when the client load is reduced, it does > 5MB/s).
What I'd like to do is persuade the system to devote more of its RAM to
buffer space, but I can't find the knob to do that. Any help would be
appreciated.
FYI, I'm not on -questions, so please CC me on any replies (or mail
directly to me and I will summarize to -questions).
Thanks for any help you can provide.
-jan-
--
Jan L. Peterson
<jlp@softhome.net>
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