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Date:      Mon, 19 Aug 2013 15:03:32 -0700
From:      Navdeep Parhar <np@FreeBSD.org>
To:        Andre Oppermann <andre@freebsd.org>
Cc:        svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Peter Grehan <grehan@freebsd.org>
Subject:   Re: svn commit: r254520 - in head/sys: kern sys
Message-ID:  <52129634.7000509@FreeBSD.org>
In-Reply-To: <52128937.1010407@freebsd.org>
References:  <201308191116.r7JBGsc6065793@svn.freebsd.org> <521256CE.6070706@FreeBSD.org> <5212587A.2080202@freebsd.org> <52128937.1010407@freebsd.org>

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On 08/19/13 14:08, Andre Oppermann wrote:
> On 19.08.2013 19:40, Peter Grehan wrote:
>>> 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...
>>
>>   I also had a virtualization work-in-progress where static mbufs were
>> allocated in the kernel and
>> M_NOFREE set.
>>
>>   Might be worth sending a prior heads-up for these type of changes.
> 
> I'm sorry for ambushing but this stuff has to be done.  I have provided
> an alternative way of handling it and I'm happy to help you with your
> use case to make it good for you and to prevent the mbuf system from
> getting bloated and hackish again.

I don't know what Peter's use case is but I'm curious about the
already-available alternative to M_NOFREE, if that's what you meant.
Can you please elaborate?

Regards,
Navdeep



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