From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
From: "Douglas A. Gwyn" <DAGwyn@null.net>
Message-ID: <3AFAA089.C45DB193@null.net>
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References: <E14xVPx-000JUF-0X@anchor-post-33.mail.demon.net>
Subject: Re: [9fans] Performance
Date: Thu, 10 May 2001 15:14:53 +0000
Topicbox-Message-UUID: 9dd9bd9e-eac9-11e9-9e20-41e7f4b1d025

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.