From mboxrd@z Thu Jan  1 00:00:00 1970
From: jmk@plan9.bell-labs.com
To: 9fans@cse.psu.edu
Subject: Re: [9fans] Performance
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Date: Thu, 10 May 2001 13:21:40 -0400
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On Thu May 10 11:31:55 EDT 2001, DAGwyn@null.net wrote:
> Richard Miller wrote:
> > Isn't there a race condition here even on a uniprocessor?  The scan
> > of the run queue and call to HLT are done with interrupts enabled:
> 
> Yes, the canonical solution, which addresses HLT on MP systems
> as well, is that whatever modifies the run queue always as a side
> effect wakes up all the dispatchers.  Some platforms support use
> of a software interrupt just as though it were a hardware
> interrupt; on others a kludge would be required, or else just
> leave it up to the clock interrupt.

Waking up other processors would require interprocessor interrupts
and that way lies madness.

A software interrupt on a uniprocessor wouldn't fix the race.

I think the correct kludge is to wait for the clock interrupt.