Re: Multiprocessor problem?
Re: Multiprocessor problem?
- Subject: Re: Multiprocessor problem?
- From: Justin Walker <email@hidden>
- Date: Mon, 17 Mar 2003 13:07:41 -0800
On Monday, Mar 17, 2003, at 12:52 US/Pacific, Mark Hunt wrote:
Hi
I have an App that crashes occasionally on dual processor machines.
The computer appears to become bus-locked, but it's hard to be sure.
Only a reset/power cycle will bring it back.
OS is 10.2.4. Any dual-cpu Mac will do!
Some minor changes to the network code seem to changed the probability
of this bug.
My networking code uses a blocking BSD socket, which places part of
the packet data into a circular array of buffers when it unblocks
(data arrives), and loops.
Is it possible for this code to execute concurrently (on both
processors at the same time) for different packets? This would
definitely explain my problem!
It theoretically not possible for this to happen [but there's a
difference between theory and practice...]. The BSD part of the kernel
uses one of two funnels to avoid running into this kind of race
condition. One of the funnels is specifically for code that touches
the networking infrastructure, and the other is for everything else.
Is this 'app' purely user-mode, or does it have some kernel code
associated with it (that you have developed)?
Regards,
Justin
--
Justin C. Walker, Curmudgeon-At-Large *
Institute for General Semantics | It's not whether you win or
lose...
| It's whether *I* win or lose.
*--------------------------------------*-------------------------------*
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