mbuf autotuning effect

[Adrian Chadd]

On 7 September 2013 12:56, Ian Lepore <ian at freebsd.org> wrote:


> I think the part of this that strikes me as strange is calling 20% of
> physical memory used for network buffers a "very low value".  It seems
> outrageously high to me.   I'd be pissed if that much memory got wasted
> on network buffers on one of our $work platforms with so little memory.
>
> So the fact that you think it's crazy-low and I think it's crazy-high
> may be a sign that it's auto-tuned to a reasonable compromise, and in
> both our cases the right fix would be to use the available knobs to tune
> things for our particular uses.
>

Well, which limit is actually being hit here? 20% of 32mb is still a lot of
memory buffers..

Now, for sizing up the needed buffers for wifi:

assuming 512 tx, 512 rx buffers for two ath NICs.

another 512+512 buffers for each arge NICs.

So, 4096 mbufs here, 2k each, so ~ 8mb of RAM.

Amusing..



-adrian