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To: Andreas Klemm <andreas@knobel.gun.de>
cc: nao@sbl.cl.nec.co.jp (Naoki Hamada), hackers@FreeBSD.org,
        current@FreeBSD.org
Subject: Re: mbuf enhancement patch 
In-reply-to: Your message of "Sun, 18 Feb 1996 20:00:52 +0100."
             <199602181900.UAA02120@knobel.gun.de> 
From: David Greenman <davidg@Root.COM>
Reply-To: davidg@Root.COM
Date: Tue, 20 Feb 1996 15:31:50 -0800
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>> I found mbuf's are not buffered though mclusters are. So here is my
>> patch for /sys/sys/mbuf.h. This seems to provide me slightly good
>> network performance.
>
>Did one of the core team members accept these patches
>officially ?! Will they go into -current ?

   No. The performance improvemment is actually quite small and the effect of
this is that any buffers malloced up to the high water mark won't be available
to other parts of the system after they are freed. We generally try to avoid
private pools of buffers unless it's absolutely necessary - which is case for
mbuf clusters, for example, which has a mechanism for maintaining reference
counts that requires them to be allocated out of a private pool.
   We once had changes similar to the ones you've provided, except we had it
so that the buffers over a certain threshold were returned back to malloc. The
problem with this was that the malloc type was lost in the process and this
messed up the malloc-type accounting (which eventually leads to malloc
failures).

-DG

David Greenman
Core-team/Principal Architect, The FreeBSD Project