Date: Thu, 4 Oct 2007 09:05:24 -0400 (EDT) From: Daniel Eischen <deischen@freebsd.org> To: Alfred Perlstein <alfred@freebsd.org> Cc: Dag-Erling Sm??rgrav <des@des.no>, hackers@freebsd.org Subject: Re: Critical Sections for userland. Message-ID: <Pine.GSO.4.64.0710040900560.9250@sea.ntplx.net> In-Reply-To: <20071004101902.GN31826@elvis.mu.org> References: <20071003015231.GJ31826@elvis.mu.org> <86zlyzqmgo.fsf@ds4.des.no> <20071004094821.GM31826@elvis.mu.org> <86ejgbqjvr.fsf@ds4.des.no> <20071004101902.GN31826@elvis.mu.org>
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On Thu, 4 Oct 2007, Alfred Perlstein wrote: > * Dag-Erling Sm??rgrav <des@des.no> [071004 03:01] wrote: >> Alfred Perlstein <alfred@freebsd.org> writes: >>> Do you have: >>> >>> a) Evidence or a paper to prove that this is a bad idea? >> >> I need evidence or a paper to prove that it is a bad idea to allow a >> userland process to hold the CPU indefinitely? >> >>> b) A helpful suggestion? >> >> Why don't you tell us what you're actually trying to do, so we can tell >> you how to do it. >> >>> c) An obvious understanding of the problem? >> >> I'll show you mine if you show me yours. > > It's not worth my time to engage someone with your mind set, you > posses neither the technical nor interpersonal skill to be useful > to me. > > For context see my replies in this thread to Kip Macy which explains > how one deals with the false-problems you mention. > > For evidence of existing, however suboptimal, run-to-completion > systems see the RTPRIO scheduling knobs. His point about telling us what you're really doing, so we might off other ways to do it is valid. We don't know why you are using homegrown user-level spinlocks instead of pthread mutexes. Priority ceiling mutexes and running in SCHED_RR or SCHED_FIFO is really what tries to address this problem, at least from the vague desciption you give. If you have tried this and they don't work correctly, then one solution is to fix them ;-) -- DE
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