Date: Tue, 04 Mar 2003 14:42:44 -0500 (EST) From: John Baldwin <jhb@FreeBSD.org> To: Hiten Pandya <hiten@unixdaemons.com> Cc: current@FreeBSD.org Subject: Re: Possible patch for limiting APs at startup Message-ID: <XFMail.20030304144244.jhb@FreeBSD.org> In-Reply-To: <20030304075707.GA1802@unixdaemons.com>
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On 04-Mar-2003 Hiten Pandya wrote: > John Baldwin (Mon, Mar 03, 2003 at 02:49:21PM -0500) wrote: >> >> On 02-Mar-2003 Juli Mallett wrote: >> > * De: Hiten Pandya <hiten@unixdaemons.com> [ Data: 2003-03-01 ] >> > [ Subjecte: Possible patch for limiting APs at startup ] >> >> Hello. >> >> >> >> Just as the topic says, do you think this patch is good enough, or gets >> >> even close to it? I have tested the patch, and it seems to do it's job >> >> in the right way. Some might call it hackery, but it's better than >> >> nothing I would suppose. >> > >> > I think your use of "cpus" to refer to APs only is silly, and also that >> > overriding mp_naps instead of using a real cpus value and using it as >> > a bounds check akin to MAXCPU, is a bit of the wrong direction. As you >> > know, the following is my patch, and it does not work, but I think, >> > personally, the behaviour is saner, in theory at least :) >> >> You should set mp_maxcpus prior to the mp_naps test so it isn't left >> invalid in the common case. Also, this patch doesn't limit HT cpu's >> at all. I could have a 4 cpu system with HTT and maxcpus=2, and I >> will end up with 4 CPU's due to 2 logical CPU's per processor. Perhaps >> this is intentional? > > Yes. It was intentional, in the sense that we only want to limit the > number of Application Processors, and not the HTT cores inside it, > because that does not make much sense, IMHO. > > Do you think that patch will be committed, or does it need improving? > (http://www.unixdaemons.com/~hiten/work/diffs/mp_machdep.c.patch) Juli's patch is much closer. Setting mp_naps directly is bogus at best. mp_naps would get reset by the mptable stuff anyways since SI_SUB_CPU is well after SI_SUB_TUNABLES. Ignoring HTT is fine. All I would really do is change juli's patch to set the max value before the if test so it is always valid. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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