From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Mon, 21 Apr 1997 13:50:26 +0100
From: miller@hamnavoe.demon.co.uk miller@hamnavoe.demon.co.uk
Subject: porting linux programs and drivers to plan9
Topicbox-Message-UUID: 5803485e-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19970421125026.rXi7aIH7r6DFD7IyMPUtz68UPXfMLmu9TCtg9d7SUhM@z>

presotto@plan9.bell-labs.com writes:

> [a fascinating account of how the Pentium Pro's out-of-order
> instruction execution breaks the Plan 9 sleep/wakeup code on
> a multi-CPU system]

It appears that the slightly different version of sleep/wakeup
given in the Volume 2 paper `Process Sleep and Wakeup on a
Shared-memory Multiprocessor' should be immune to the effects
of weak memory coherency, because the shared variables are
referenced only inside a lock/unlock pair.  Is this right?

Perhaps the moral is that it's better to be conservative with
locks than to trust hardware designers to do what we expect.

-- Richard Miller