bge(4) sysctl tuneables -- a blast from the past.

[YongHyeon PYUN]

On Tue, Apr 16, 2013 at 05:14:54PM +1000, Bruce Evans wrote:
> On Tue, 16 Apr 2013, YongHyeon PYUN wrote:
> 
> >On Mon, Apr 15, 2013 at 03:35:56PM -0700, Sean Bruno wrote:
> >>
> >>>FreeBSD has too many knobs, but it would be nice if the bge defaults 
> >>>weren't
> >>>so broken, so that they don't need overriding.
> >>
> >>So many knobs ... well here's more.  :-)
> >>
> >>http://people.freebsd.org/~sbruno/bge_config_update.txt
> >>
> >>At least this gets a man page update with references to manuals.
> >
> >You have to change BGE_STD_RX_RING_CNT to change number of RX
> >descriptors. It's hard-coded and it needs much more work to change
> >that. And I don't see any reason to modify that though(Max # of RX
> >descriptor is 512).
> 
> I thought that at first too, but a simple change along these lines
> must be OK since old versions had it.  There was a BGE_SSLOTS "option"
> that was 256.  This was used instead of BGE_STD_RX_RING_CNT in much
> the same places that the tunable is now used, since 512 bds used to
> be a lot.  From FreeBSD-~5.2:

I'm afraid that will allocate more DMAable memory than specified
with the tunable and the amount of data that bus_dmamap_sync(9)
have to handle is the same as before.