Date: Fri, 20 Sep 2002 00:08:38 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: Bill Huey <billh@gnuppy.monkey.org> Cc: freebsd-arch@freebsd.org Subject: Re: New Linux threading model Message-ID: <Pine.BSF.4.21.0209192345090.16925-100000@InterJet.elischer.org> In-Reply-To: <20020920031423.GA3380@gnuppy.monkey.org>
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HI and thanks for the pointers. it's interesting that the features that they talk about as being difficult and 'required' generally just "fall out" of the KSE implimentation. A lot of the shortcomings of M:N that they quote don't apply to the KSE schemes either.. for example: They talk a lot about making signals per-process (uber-process that is). Signals in KSE are automatically per process. They talk of the difficulty of making SIGSTOP work, and are very very proud that they have it working over the entire uber-process, yet KSE has had this working since the very first test program. I still think they are dressing up a Bull to make it fit in in the chicken coop. The sad thing is that we'll have to implement their kernel side stuff for binary compatibility, so we'll have chickens AND a bull dressed like a bunch of chickens. Market share has it's advantages. Of course We can emulate them but they'll never be able to emulate us. You can make a bunch of chickens look like anything a bull dressed as a bunch of chickens can look like, but the converse is not true without killing the bull. :-) Hell, if we've really screwed up, hey there's always 4.7 as a base :-) What they have decided to do is not a stupid move. But I disagree with some of their assertions. I first heard that method of doing threads expounded by Kirk in the BSD4.4 internals class in 1992 (or was that 91?). It sounded feasible then and it is stiff feasible. In fact I remember discussing it with Linus once a long time ago at a USENIX forum. (before he became hard to find under the crowds). I just happen to think that what we have will be very sweet when you see it working. On Thu, 19 Sep 2002, Bill Huey wrote: > > Hello, > > I got this off of lkml: > > http://marc.theaimsgroup.com/?l=linux-kernel&m=103248252713576&w=2 > > paper: > http://people.redhat.com/drepper/nptl-design.pdf > > They basically went to (kept) a 1:1 threading model, but added a bunch of > things to the kernel so that stuff like signal handling, pid, thread suspension > via signal notification, etc... are all very conformant to Posix threading > now. > > In their paper, they talk briefly about how they came to the decision that > 1:1 is better than M:N and why they chose that against variants of M:N > including scheduler activations, a cross process fast-path synchronization > primitive called "futexes", etc... > > bill > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-arch" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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