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Date:      Sat, 6 May 1995 11:37:22 +0800 (CST)
From:      Brian Tao <>
To:        David Greenman <davidg@Root.COM>
Subject:   Re: Heavy HTTPD serving on 2.0-950412 
Message-ID:  <>
In-Reply-To: <199505051840.LAA04219@corbin.Root.COM>

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On Fri, 5 May 1995, David Greenman wrote:
> options         "NMBCLUSTERS=1024"

    Yep, found it in the mail archives after John Fieber updated them
on the Web site.

> This will give you twice as many buffers (or 4 times if you don't have
> GATEWAY in your kernel). Double the above to 2048 if the problem
> persists. I use 8192 on wcarchive, which is enough for 1000 ftp users
> (about 2000 TCP connections).

    Ah, my next two questions already answered.  ;-)  I ran an 11-hour
test with NCSA httpd 1.4 last night with 4 local Ethernet clients and
60 remote clients.  No problems with NMBCLUSTERS set to 1024.  Doing a
'netstat -n | grep ^tcp' showed between 450 and 520 open connections,
almost all in TIME_WAIT and nearly 16K in the send queue (not
surprisingly, all to sites across the Pacific).  I haven't done the
analysis yet, but it looks like NCSA's preforking helps out a whole
lot here.  I'm guessing about 600,000 accesses per day with a load
average of less than 1.00.  :)

    'systat -mbuf' shows this:

                    /0   /1   /2   /3   /4   /5   /6   /7   /8   /9   /10
     Load Average   |

          /0   /5   /10  /15  /20  /25  /30  /35  /40  /45  /50  /55  /60
data      XXXXXX
headers   XXXXX

    Ummm... what should I be looking for, if I think I'm running out
of mbufs?  Add up all the X's and see if they exceed NMBCLUSTERS?  How
about checking a kernel's NMBCLUSTERS setting?  I didn't see anything
in the sysctl man page.

> >Active Internet connections
> >Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)
> >netstat: kvm_read: kvm_read: Bad address
>    Rebuild netstat; the networking structurs in the kernel have changed.

    Got it.  Thanks.

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