Date: Fri, 21 Dec 2007 03:16:15 -0500 (EST) From: Daniel Eischen <deischen@freebsd.org> To: David Xu <davidxu@freebsd.org> Cc: freebsd-threads@freebsd.org Subject: Re: threads/118910: Multithreading problem Message-ID: <Pine.GSO.4.64.0712210310090.20251@sea.ntplx.net> In-Reply-To: <476B7476.3010509@freebsd.org> References: <200712210700.lBL707MZ002071@freefall.freebsd.org> <Pine.GSO.4.64.0712210228030.20251@sea.ntplx.net> <476B6E35.508@freebsd.org> <Pine.GSO.4.64.0712210243120.20251@sea.ntplx.net> <476B7476.3010509@freebsd.org>
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On Fri, 21 Dec 2007, David Xu wrote: > Daniel Eischen wrote: > >> I don't think it is as big a change as you think it is. We already >> have several layers of priorities (interrupt, time-share, idle, ?). >> All threads belong to these classes. As long as priority inheritence >> works, there should be no problems. The problems seem to occur when >> we try to inject artificial priorities into threads, like using >> msleep(). I think we are better off just letting threads run based >> on their own base priority and whatever their inherited priority is. >> > > For test purpose, you may try to ignore thread priority parameter > in msleep(), I didn't test this, but it does change the FreeBSD > behavior. I don't know any side effect since I am unable to test > all applications in the world, maybe you can start a project to hack > it ? I'll take a look at trying that. I should be able to figure out how to get msleep to ignore the priority. But I think the missing piece is the interrupt routines - they need to create their mutexes and CVs so that they are more like priority ceiling mutexes. Any thread (even non-interrupt threads) that takes one of these mutexes needs to have its priority raised as well as blocking the interrupt (for fast interrupts anyway) until the mutex is released. -- DE
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