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Re: Can't change kern.mbuf.nmbclusters on evbarm?

On Wed, Jun 29, 2011 at 09:09:54PM -0700, Andy Ruhl wrote:
> So I tried increasing kern.mbuf.nmbclusters, but it gives me an error:
> root@dockstar:~ # sysctl kern.mbuf.nmbclusters
> kern.mbuf.nmbclusters = 1792
> root@dockstar:~ # sysctl -w kern.mbuf.nmbclusters=2048
> sysctl: kern.mbuf.nmbclusters: sysctl() failed with Invalid argument
> I also tried setting a kernel option and re-compiling, but it doesn't
> change this value.

How much memory do you have? The new logic is supposed to cap
nmbclusters at 1/4 of the physical memory OR 1/2 of the KVA for
architectures without direct memory mapping. Whatever is smaller.
ARM has an additional limit of 64MB (NMBCLUSTERS_MAX). IIRC to avoid
exhausting KVA for that purpose.


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