svn commit: r254520 - in head/sys: kern sys

[Navdeep Parhar]

On 08/19/13 04:16, Andre Oppermann wrote:
> Author: andre
> Date: Mon Aug 19 11:16:53 2013
> New Revision: 254520
> URL: http://svnweb.freebsd.org/changeset/base/254520
> 
> Log:
>   Remove the unused M_NOFREE mbuf flag.  It didn't have any in-tree users
>   for a very long time, if ever.
>   
>   Should such a functionality ever be needed again the appropriate and
>   much better way to do it is through a custom EXT_SOMETHING external mbuf
>   type together with a dedicated *ext_free function.
>   
>   Discussed with:	trociny, glebius
> 
> Modified:
>   head/sys/kern/kern_mbuf.c
>   head/sys/kern/uipc_mbuf.c
>   head/sys/sys/mbuf.h
> 

Hello Andre,

Is this just garbage collection or is there some other reason for this?

I recently tried some experiments to reduce the number of mbuf and
cluster allocations in a 40G NIC driver.  M_NOFREE and EXT_EXTREF proved
very useful and the code changes to the kernel were minimal.  See
user/np/cxl_tuning.  The experiment was quite successful and I was
planning to bring in most of those changes to HEAD.  I was hoping to get
some runtime mileage on the approach in general before tweaking the
ctors/dtors for jumpbo, jumbo9, jumbo16 to allow for an mbuf+refcnt
within the cluster.  But now M_NOFREE has vanished without a warning...

Regards,
Navdeep