Date: Thu, 30 Sep 2004 21:40:21 +0200 From: Marius Strobl <marius@alchemy.franken.de> To: Ken Smith <kensmith@cse.Buffalo.EDU> Cc: cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/sparc64/sparc64 machdep.c Message-ID: <20040930214021.A84755@newtrinity.zeist.de> In-Reply-To: <20040930192443.GE19077@electra.cse.Buffalo.EDU>; from kensmith@cse.Buffalo.EDU on Thu, Sep 30, 2004 at 03:24:43PM -0400 References: <200409301438.i8UEcx89022771@repoman.freebsd.org> <48971.1096571367@critter.freebsd.dk> <20040930192443.GE19077@electra.cse.Buffalo.EDU>
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On Thu, Sep 30, 2004 at 03:24:43PM -0400, Ken Smith wrote: > On Thu, Sep 30, 2004 at 09:09:27PM +0200, Poul-Henning Kamp wrote: > > In message <200409301438.i8UEcx89022771@repoman.freebsd.org>, Ken Smith writes: > > >kensmith 2004-09-30 14:38:59 UTC > > > > > > FreeBSD src repository > > > > > > Modified files: > > > sys/sparc64/sparc64 machdep.c > > > Log: > > > This along with v1.6 of counter.c fixes some timecounter issues on > > > MP machines (hopefully). CPU timers are OK on UP machines but we > > > don't keep the timers in sync on MP machines so if the CPU's timer > > > is chosen as the primary timecounter it's possible for time to > > > not be monotonically increasing because different CPU's counters > > > may be used at different times. But the CPU's counters are otherwise > > > one of the higher quality counters available. So, on UP machines > > > we'll use a relatively high quality value but on MP machines we'll > > > use a quality that should prevent the CPU's counters from being chosen. > > > > The 'microsecond clock' is present in all suns so we don't leave any > > machines without timecounters, right ? > > > > Funny you should ask. Testing the first version of this patch was how > we found the bug in counter.c - the machine I booted the test kernel > with happened to decide the counter-timer wasn't suitable either due > to the bug and it came up with no timecounters. You should see what > happens to a machine that's not keeping time. :-) > > Marius has device maps for virtually all known Sparc hardware and > he said all of the MP machines do have the counter-timer available Well, that's an exaggeration :) But I think I have enough to say that all Sun UltraSparc II boards have a counter-timer device. > in them. Only the IIi and IIe processor based systems don't and > they're only UP machines. > > We are drastically low on timecounter-capable devices on sparc64 > though, it seems the counter-timer and the CPU are about all there > is. > > If this makes you nervous and if you have any suggestions I'm all > ears. >
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