From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <64a6fa23d8a01d86312954ab451692d0@terzarima.net>
From: Charles Forsyth <forsyth@terzarima.net>
Date: Sat, 12 Jun 2010 23:15:31 +0100
To: 9fans@9fans.net
In-Reply-To: <AANLkTimFWKiVUowEyMOehT5r3fs--xdv25eS05g8zoG5@mail.gmail.com>
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Subject: Re: [9fans] 9vx, kproc and *double sleep*
Topicbox-Message-UUID: 31e40c40-ead6-11e9-9d60-3106f5b1d025

>in Linux parlance, Plan 9 is a "preemptible" kernel. Interrupt handlers can be interrupted, so to speak.

interrupt handlers are not normally interruptible during the interrupt
processing, but rather at the end (eg, when anyhigher, anyready or preempted
is called).

processes running at non-interrupt level in the kernel can be interrupted unless they are splhi
or using ilock.

>Except for the clock interrupt handler

that's only because the clock interrupt handler directly or indirectly (eg,
via sched) calls spllo, and other trap or interrupt handlers could do that.