From owner-freebsd-arch@FreeBSD.ORG  Mon Mar 22 20:42:41 2010
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To: Alexander Sack <pisymbol@gmail.com>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Mon, 22 Mar 2010 15:07:56 -0400."
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Date: Mon, 22 Mar 2010 20:42:37 +0000
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Cc: scottl@samsco.org, mav@freebsd.org, freebsd-current@freebsd.org,
	ivoras@freebsd.org, freebsd-arch@freebsd.org
Subject: Re: Increasing MAXPHYS 
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In message <3c0b01821003221207p4e4eecabqb4f448813bf5a8a8@mail.gmail.com>, Alexa
nder Sack writes:

>Am I going crazy or does this sound a lot like Sun/SVR's stream based
>network stack?

That is a good and pertinent observation.

I did investigate a number of optimizations to the g_up/g_down scheme
I eventually adopted, but found none that gained anything justifying
the complexity they brought.

In some cases, the optimizations used more CPU cycles than the straight
g_up/g_down path, but obviously, the circumstances are vastly different
with CPUs having 10 times higher clock, multiple cores and SSD disks,
so a fresh look at this tradeoff is in order.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.