From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@quanstro.net>
Date: Fri,  1 Jul 2011 14:01:28 -0400
To: 9fans@9fans.net
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References: <20110701160026.0db036cd@leffe.cs.bell-labs.com>
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Subject: Re: [9fans] why not halt in x86 multicore
Topicbox-Message-UUID: f8f7d9ec-ead6-11e9-9d60-3106f5b1d025

>
> interprocessor interrupts are the obvious solution
> but no one has bothered to implement them.
>

i almost mentioned this, and it's on my list.  i just haven't
had the time.  it turns out that a naive implementation of
ipi'ing 1 proc per wakeup will have to watch out for the
same races that bedeviled multiprocessor sleep/wakeup.

the really naive solution of waking 'em all up is a very
bad idea because you'll have n-1 procs duking it out
over the run queue.

perhaps i just ignorant of the standard solution.
or perhaps the sleep/wakeup model isn't the right one
for the situation.

- erik