4.8-STABLE Kernel Panic with dummynet options.

[Sergey A. Osokin]

On Wed, Apr 09, 2003 at 05:03:03PM +0300, Dmitry Pryanishnikov wrote:
> On Wed, 9 Apr 2003 15:13:53 +0400, Sergey A. Osokin wrote:
> >> options    NMBCLUSTERS=1024
> >> options    NMBUFS=4096
> >
> > What is the NMBUFS? You talk about NSFBUFS?
> 
>  Nope, there is NMBUFS - number of single mbufs vs NMBCLUSTERS for
> mbuf clusters. You can see current usage:
> 
> root at atlantis# netstat -m
> 1080/2736/32768 mbufs in use (current/peak/max):
>         1010 mbufs allocated to data
>         70 mbufs allocated to packet headers
> 781/2434/16384 mbuf clusters in use (current/peak/max)
> 
> (1st line for mbufs, 4th for mbuf clusters) and adjust both values in
> /boot/loader.conf:
> 
> kern.ipc.nmbufs="32768"         # Number of mbufs
> kern.ipc.nmbclusters="16384"    # Number of mbuf clusters
> 
> Note the following sanity check in kernel:
> 
>         /* Sanity checks */
>         if (nmbufs < nmbclusters * 2)
>                 nmbufs = nmbclusters * 2;
> 
> > AFAIK 1024 is very-very small value for NMBCLUSTERS.
> 
>  Well, it depends ;) Really, one of my routers shows the following:
> 
> dmitry at cs37$ netstat -m
> 69/560/6144 mbufs in use (current/peak/max):
>         69 mbufs allocated to data
> 35/206/1536 mbuf clusters in use (current/peak/max)
> 
> after uptime of 46 days (total traffic up to several Mbit/s, 6 network
> interfaces, dummynet in use).
> 
> On Wed, 9 Apr 2003 16:00:46 +0400, Sergey A. Osokin wrote:
> >> And what about the HZ value?
> >
> > AFAIK its compile time option.
> 
>  It's also boot-time tunable long time ago, see 4.4-RELEASE release notes:
> 
>    The maxusers kernel configuration parameter is now a boot-time tunable
>    variable. The kernel parameters derived from maxusers are now also
>    tunables and can be overridden at boot-time. The hz parameter is also now
>                                                     ^^^^^^^^^^^^
>    a tunable.
> 
>  So one can just set HZ to some reasonable value (200, 500, 1000 - it depends
> also) in loader.conf:
> 
> kern.hz="200"                   # Clock interrupts per second

Looks like time to rewrite handbook/faq/tuning(7)/etc. :-)

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