[WIP][PATCHES] Network xmit batching

[jamal <hadi@cyberus.ca>]

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Folks,

While Krishna and I have been attempting this on the side, progress has
been rather slow - so this is to solicit for more participation so we
can get this over with faster. Success (myself being conservative when
it comes to performance) requires testing on a wide variety of hardware.

The results look promising - certainly from a pktgen perspective where
performance has been known in some cases to go up over 50%.
Tests by Sridhar on a low number of TCP flows also indicate improved
performance as well as lowered CPU use.
 
I have setup the current state of my patches against Linus tree at:
git://git.kernel.org/pub/scm/linux/kernel/git/hadi/batch-lin26.git

This is also clean against 2.6.22-rc4. So if you want just a diff that
will work against 2.6.22-rc4 - i can send it to you.
I also have a tree against Daves net-2.6 at 
git://git.kernel.org/pub/scm/linux/kernel/git/hadi/batch-net26.git
but iam abandoning that effort until we get this stable due to the
occasional bug that cropped up(like e1000).

I am attaching a pktgen script. There is one experimental parameter
called "batch_low" - for starters just leave it at 0 in order to reduce
experimental variance. If you have solid results you can muck around
with it.
KK has a netperf script he has been using - if you know netperf your
help will really be appreciated in testing it on your hardware.
KK, can you please post your script?
Testing with forwarding and bridging will also be appreaciated.
Above that, suggestions to changes as long as they are based on
verifiable results or glaringly obvious changes are welcome. My
preference at the moment is to flesh out the patch as is and then
improve on it later if it shows it has some value on a wide variety of
apps. As the subject is indicating this is a WIP and as all eulas
suggest "subject to change without notice". 
If you help out, when you post your results, can you please say what
hardware and setup was?

The only real driver that has been changed is e1000 for now. KK is
working on something infiniband related and i plan (if noone beats me)
to get tg3 working. It would be nice if someone converted some 10G
ethernet driver.

cheers,
jamal

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