Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 30 Sep 2002 10:49:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 30 Sep 2002 10:49:49 -0400 Received: from 12-237-170-171.client.attbi.com ([12.237.170.171]:74 "EHLO wf-rch.cirr.com") by vger.kernel.org with ESMTP id ; Mon, 30 Sep 2002 10:49:47 -0400 Message-ID: <3D9865B5.7020006@acm.org> Date: Mon, 30 Sep 2002 09:54:45 -0500 From: Corey Minyard User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0rc3) Gecko/20020523 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Buddy Lumpkin CC: "'Bill Davidsen'" , "'Peter Waechtler'" , "'Larry McVoy'" , linux-kernel@vger.kernel.org, "'ingo Molnar'" Subject: Re: [ANNOUNCE] Native POSIX Thread Library 0.1 References: <000001c2680f$a13af930$0472e50c@peecee> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3656 Lines: 124 Buddy Lumpkin wrote: >Sun introduced a new thread library in Solaris 8 that is 1:1, but it did >not replace the default N:M version, you have to link against >/usr/lib/lwp. > >http://supportforum.sun.com/freesolaris/techfaqs.html?techfaqs_2957 >http://www.itworld.com/AppDev/1170/swol-1218-insidesolaris/ > >I was at a USENIX BOF on threads in Boston year before last and Bill >Lewis was ranting about how the N:M model sucks. Christopher Provenzano >was right there and didn't seem to add any feelings one way or the >other. > >Regards, > >--Buddy > I heard this a while ago, and talked with someone I knew who had inside information about this. According to that person, Sun will be switching the default threads library to 1:1 (It looks like from the document referenced below it is Solaris 9). In various benchmarks, sometimes M:N won, and sometimes 1:1 won, so performance was a wash. The main problem was that they could never get certain things to work "just right" under an M:N model, the complexity of M:N was just too high to be able to get it working 100% correctly. He didn't have specific details, though. Having implemented a threads package with prority inheritance, I expect that doing that with an M:N thread model will be extremely complex. With activations is possible, but that doesn't mean it's easy. It's hard enough with a 1:1 model. A scheduler with good "global" properties (for example, a scheduler that guaranteed time share to classes of threads that occur in different processes) would be difficult to implement properly, too. Complexity is the enemy of reliability. Even if the M:N model could get slightly better performance, it's going to be very hard to make it work 100% correctly. I personally think the NPT is going in the right direction on this one. -Corey > >-----Original Message----- >From: linux-kernel-owner@vger.kernel.org >[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Bill Davidsen >Sent: Monday, September 23, 2002 12:15 PM >To: Peter Waechtler >Cc: Larry McVoy; linux-kernel@vger.kernel.org; ingo Molnar >Subject: Re: [ANNOUNCE] Native POSIX Thread Library 0.1 > >On Mon, 23 Sep 2002, Peter Waechtler wrote: > > > >>Am Montag den, 23. September 2002, um 12:05, schrieb Bill Davidsen: >> >> >> >>>On Sun, 22 Sep 2002, Larry McVoy wrote: >>> >>> >>> >>>>On Sun, Sep 22, 2002 at 08:55:39PM +0200, Peter Waechtler wrote: >>>> >>>> >>>>>AIX and Irix deploy M:N - I guess for a good reason: it's more >>>>>flexible and combine both approaches with easy runtime tuning if >>>>>the app happens to run on SMP (the uncommon case). >>>>> >>>>> >>>>No, AIX and IRIX do it that way because their processes are so >>>> >>>> >bloated > > >>>>that it would be unthinkable to do a 1:1 model. >>>> >>>> >>>And BSD? And Solaris? >>> >>> >>Don't know. I don't have access to all those Unices. I could try >> >> >FreeBSD. > >At your convenience. > > > >>According to http://www.kegel.com/c10k.html Sun is moving to 1:1 >>and FreeBSD still believes in M:N >> >> > >Sun is total news to me, "moving to" may be in Solaris 9, Sol8 seems to >still be N:M. BSD is as I thought. > > >>MacOSX 10.1 does not support PROCESS_SHARED locks, tried that 5 >> >> >minutes > > >>ago. >> >> > >Thank you for the effort. Hum, that's a bit of a surprise, at least to >me. > > > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/