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Date:      Tue, 11 Dec 2001 16:14:55 -0800
From:      Luigi Rizzo <rizzo@aciri.org>
To:        net@freebsd.org
Subject:   Polling code at http://info.iet.unipi.it/~luigi/polling/
Message-ID:  <20011211161454.B23443@iguana.aciri.org>

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[Bcc to committers and -stable as relevant there, but
please keep the discussion on -net if any]

I have put up a web page with the latest version of the device
polling patches, both for -stable and -current, at

	http://info.iet.unipi.it/~luigi/polling/

so new versions will be available through there, together with
additional documentation, code and references.

Compared to the code recently pulled out from -stable, what you
can find now at the above URL has the following improvements:

 * "scheduling" code which lets you control in a reasonably
   fine-grained way the sharing of CPU between kernel (polling)
   and userland. You can now do something like

	sysctl kern.polling.user_frac=40

   to reserve 40% of the CPU time to userland processes
   (assuming there is enough work to do). Default value is 50.

 * a restructured polling loop which prevents livelock and
   unfairness even when the standard (no fastforwarding) path
   is used.

Together with the kern.polling.enable variable, kern.polling.user_frac
is the only tunable parameter that you need to care about, and the
default value should be a reasonable one.

It would be great if some of you committers would have the time to
have a look at the -current version, or possibly even try it on
Alpha boxes (I think overall there is only one or two lines of MD
code), and send feedback.

	thanks
	luigi
----------------------------------+-----------------------------------------
 Luigi RIZZO, luigi@iet.unipi.it  . ACIRI/ICSI (on leave from Univ. di Pisa)
 http://www.iet.unipi.it/~luigi/  . 1947 Center St, Berkeley CA 94704
 Phone: (510) 666 2927
----------------------------------+-----------------------------------------

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