interrupt latency and driver locking

[Harti Brandt]

On Sat, 20 Sep 2003, M. Warner Losh wrote:

MWL>In message: <XFMail.20030920142934.jdp at polstra.com>
MWL>            John Polstra <jdp at polstra.com> writes:
MWL>: there will be no link changes except at bootstrap and shutdown.
MWL>
MWL>For server machines.  For laptops, these events happen more often.
MWL>However, for most laptops, the rate that they happen is typically on
MWL>less than 1/hour.  Still rare enough to not worry about optimizing it
MWL>and your other points are good.  I just wanted to make sure that it
MWL>wasn't optimized to the point where disconnecting the cable from the
MWL>laptop to move it accross the room, or another room doesn't cause huge
MWL>problems.

Perhaps the polling should be configurable., I struggled with this a year
ago in the xl driver. I have an application that does real-time satellite
simulation over two ethernet links with HZ=10000. This works really
perfect (timing errors are not larger than 200usecs) except for the MII
polling. With help from msilby we could cut down the mii polling delay
from 8msecs to below 1msec. But, because that's still too much for my
application, I have simply commented out the polling calls in the mii
source. I suppose there are other application (servers) where one could
simply switch them off. This could perhaps be done with a sysctl in
mii(4).

harti
-- 
harti brandt,
http://www.fokus.fraunhofer.de/research/cc/cats/employees/hartmut.brandt/private
brandt at fokus.fraunhofer.de, harti at freebsd.org