Increasing MAXPHYS

Poul-Henning Kamp phk at
Mon Mar 22 20:42:41 UTC 2010

In message <3c0b01821003221207p4e4eecabqb4f448813bf5a8a8 at>, 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 at 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.

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