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Date: Sun, 21 Aug 2005 20:41:16 +0400
From: Dmitry Mityugov <dmitry.mityugov@gmail.com>
To: Garrett Cooper <youshi10@u.washington.edu>
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References: <20050821123959.56599.qmail@web33304.mail.mud.yahoo.com>
	<430894AA.8060605@u.washington.edu>
Cc: freebsd-questions@freebsd.org
Subject: Re: polling decreases throughput ~50%
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On 8/21/05, Garrett Cooper <youshi10@u.washington.edu> wrote:
...
>     Heh. We just discussed polling vs interrupts in an embedded systems
> class this past quarter. Interrupts are better for more intermittent use
> and polling is better for more frequent use, as polling is actually a
> deadloop of course-for checking a flag most of the time-with potentially
> a lot of wasted clock cycles before a context switch is made and the
> task that was being polled for is run. Also, considering that actual
> computer hardware isn't going to be running 100% of the time (except for
> the CPU running idle tasks and stuff), interrupts are by far the better
> way to go in general. But yeah... too many interrupts are bad as well...
>     Anyhow, that was sidetracking a bit :).

Probably a good solution to this problem is to switch to the polling
mode when you get an interrupt (or a few interrupts in a row), and
switch back to the interrupt mode when the line has been idle for a
while.

--=20
Dmitry Mityugov, St. Petersburg, Russia
I ignore all messages with confidentiality statements

"We live less by imagination than despite it" - Rockwell Kent, "N by E"