From mboxrd@z Thu Jan 1 00:00:00 1970 From: lm@mcvoy.com (Larry McVoy) Date: Thu, 27 Nov 2014 12:55:21 -0800 Subject: [TUHS] What's with the DZ-11? In-Reply-To: References: Message-ID: <20141127205521.GJ9497@mcvoy.com> On Fri, Nov 28, 2014 at 06:45:38AM +1100, Dave Horsfall wrote: > On Thu, 27 Nov 2014, Dave Horsfall wrote: > > > I've seen a couple of less than flattering references here; what was the > > problem with them? > > A number of responses, all of which boil down to the same thing, viz: an > interrupt on each character. > > I know that, which is why we (UNSW) re-worked the driver; I can't believe > that we were the only ones who did so. It cleaned out as many silos as it > could, possibly even by disabling interrupts completely and using clock > ticks; I can't remember. This problem is old as the hills, at SGI we did similar stuff for networking cards. We could run something like 8 HIPPI cards at full bandwidth with some 200mhz MIPS cpus. Lots of work in the networking stack to go get the next packet if it was there after we did this one.