Date: Mon, 01 Nov 1999 21:25:26 +0900 From: "Daniel C. Sobral" <dcs@newsguy.com> To: Daniel Eischen <eischen@vigrid.com> Cc: freebsd-arch@freebsd.org Subject: Re: Threads goals version II Message-ID: <381D86B6.3D20E0E7@newsguy.com> References: <199911010443.XAA26092@pcnet1.pcnet.com>
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[slightly off-topic] Daniel Eischen wrote: > > What happens under LinuxThreads? I'd expect an rfork'd process to > get an equal share of processor time as it's parent. If I create > 10 threads with PTHREAD_SCOPE_SYSTEM, I expect to have 10 LWPs (or > rfork'd processes). What I am trying to say is that an application > that creates 10 threads with PTHREAD_SCOPE_SYSTEM gets more processor > time than 8 threads with PTHREAD_SCOPE_SYSTEM and 2 threads with > PTHREAD_SCOPE_PROCESS. Some people (most people on the FreeBSD campus who have been involved with threads, it would seem) think that having more threads for the purpose of increasing your time slice is bad behavior, to say the least. Unix have a mechanism to adjust the relative priority between processes, which is called priority. If a process is supposed to eat more cpu time than others, it is given a lower priority than the others. Having a programmer get around the admin mechanism to adjust process priority through use of threads might led to a situation where competing users end up bogging down the whole system while fighting for cpu time. I can see clear disadvantages in allowing a process cpu time be allotted according to how many threads it has. Do you see any particular disadvantage to nice(1)? MMmmm... I should removed this last sentence before sending this message, it comes too aggressive, but I can't think of any better way of getting the point across. Anyway, this is the "contention" point that has been mentioned. Many people here _want_ all processes to be equal, no matter how many threads they run. Instead of trying to convince people to see the light, just ask that your dissent be noted, or that both capabilities be present. -- Daniel C. Sobral (8-DCS) dcs@newsguy.com dcs@freebsd.org "People call him Neutron Star, 'cuz he's so dense lights bends around him." To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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