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Postings from August 2001
Re: Opcode Dispatch
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From:
Uri Guttman
Date:
August 6, 2001 15:05
Subject:
Re: Opcode Dispatch
Message ID:
200108062205.SAA19684@home.sysarch.com.
>>>>> "BCW" == Bryan C Warnock <bwarnock@capita.com> writes:
BCW> I was doing some thinking on the event loop (and how to tie it in
BCW> later), and ran into a question. Given the current priority
BCW> idea, how far does a priority stretch? (Horrible description, so
BCW> let me give an example. Say SIGALRM has been determined to be
BCW> priority 4 and you are processing regular code (prioirity 0).
BCW> Perl receives the signal and generates an event of prioirty 4.
BCW> Perl then switches to that priority level to process the event.
BCW> If the event has a callback (to regular Perl code), does the
BCW> callback's code (beyond the actual dispatch) run at PRI 4, or 0?
BCW> At what point do you revert to the lower priority and allow other
BCW> events to be handled?)
callbacks are run at the priority level of the triggering event. they
can be preempted by a higher level event/callback but not by a lower
one. i don't see any reason to allow lowering the current priority level
in the event loop. that would only make sense in a real kernel where a
driver is doing a long running operation that may want to be interrupted
by a lower priority device.
uri
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