Date: Mon, 17 Jan 2000 00:55:04 -0500 (EST) From: Alexander Litvin <archer@lucky.net> To: hackers@freebsd.org Subject: Re: Preemptiveness of FreeBSD threads Message-ID: <200001170555.AAA47274@unknown.nowhere.org> In-Reply-To: <200001170423.XAA10093@pcnet1.pcnet.com>
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In article <200001170423.XAA10093@pcnet1.pcnet.com> you wrote: >> Now, as I understand, userspace threads in FreeBSD are preemptive. >> So, though my 11 threads are all computational and do not do >> any syscalls, sleeps, sched_yield, whatever -- newertheless, >> the program should not be stuck in one thread. And it seems to >> be sometimes true. But only sometimes! >> >> Depending on the phase of the moon (it seems) sometimes my >> program gives (after ^C): >> >> ^C >> Thread 0x00: 0 >> Thread 0x01: 0 >> Thread 0x02: 0 >> Thread 0x03: 0 >> Thread 0x04: 0 >> Thread 0x05: 0 >> Thread 0x06: 0 >> Thread 0x07: 0 >> Thread 0x08: 0 >> Thread 0x09: 0 >> Thread 0x0a: 488133092 > Hmm, I can't get this to occur with your test program. I've tried > it several times and the threads seem to be scheduled properly. > If you figure out how to repeat this without relying on phases of > the moon, I'd be interested in hearing how. That's what makes it most wierd for me -- I am not able to determine conditions when it gives a "wrong" result. I'll keep trying though. I also could probably compile libc_r with debug info and set a breakpoint somewhere in threads scheduler to see what's going on. Or, because it is time-related, it is not a good idea? Then printfs in libc_r -- will they work? Could you suggest a good place to start looking? As I said, it seems to go in periods -- for some time everything is normal, and then for some time -- bullshit :-\ You may try to repeat it after some time. It may also be hardware dependent (?) > Are you running NTP or changing the time? That idea also came to me, but no -- I don't have NTP, and I don't change the time. And as I said, the interrupts seem to keep being delivered to the process. > Dan Eischen > eischen@vigrid.com --- After living in New York, you trust nobody, but you believe everything. Just in case. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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