Re: NMBCLUSTERS warning - sysctl fix?

[Donald Lee <MacPPC2%caution.icompute.com@localhost>]

>On Mon, Mar 24, 2008 at 08:02:58PM -0500, Donald Lee wrote:
>> I got a brief hang today on my production server running NetBSD 2.1 PPC:
>> 
>> Mar 24 13:57:07 mercy /netbsd: WARNING: mclpool limit reached; increase 
>> NMBCLUSTERS 
>> Mar 24 13:58:07 mercy /netbsd: WARNING: mclpool limit reached; increase 
>> NMBCLUSTERS 
>> Mar 24 14:00:08 mercy last message repeated 2 times
>> Mar 24 14:05:09 mercy last message repeated 5 times
>> 
>> In the NetBSD docs, there is some advice:
>> 
>>      http://netbsd.org/docs/kernel/#mclpool-limit
>> 
>> What I have done is set up /etc/sysctl.conf, and put:
>> 
>>      # Server gets busy sometimes.  Bump up network resources
>>      # number of "mbuf clusters"?  Default of 1024 too small.
>>      kern.mbuf.nmbclusters=4096
>> 
>> in it.  This seems to work fine, but I apparently have to bump it up again.
>> 
>> The docs (above) suggest the "sysctl -w", and also suggest patching the
>> kernel.  At the end of the section it says:
>> 
>>      Combining this, and patching the binary, would mean no need to
>>      build a new kernel or reboot.
>> 
>> Is there some reason that the sysctl.conf approach is insufficient?  Do I 
>> need
>> to set sysctl *and* patch the kernel for some reason?
>
>It depends on how the MCL pool is implemented on a particular architecture.
>Some can grow it on the fly, come can't. I think alpha can grow
>it on the fly (so the sysctl method will work) but i386/amd64 can't
>(so need the kenrel patch method). I don't know in which category
>macppc is though, but sysctl -w should return you an error if
>it can't be grown on the fly.
>

sysctl -w works, so it must be able to grow on the fly, and my sysctl.conf
is probably sufficient.

Thanks!  I'll pump it up to 8192 and see if that helps.

-dgl-