From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Fri, 04 Jun 2004 16:51:32 +0000 Subject: Re: sched_clock - cont'd Message-Id: <16576.43156.627974.180637@napali.hpl.hp.com> List-Id: References: <40C08A29.A46DF067@nospam.org> In-Reply-To: <40C08A29.A46DF067@nospam.org> MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable To: linux-ia64@vger.kernel.org >>>>> On Fri, 04 Jun 2004 16:41:45 +0200, Zoltan Menyhart said: Zoltan> David, Since I applied your patch, I re-booted my Tiger-4 Zoltan> about 10 times and I got twice the following Oops: Zoltan> CPU 3: base freq=199.453MHz, ITC ratio=13/2, ITC Zoltan> freq=1296.444MHz+/--1ppm Calibrating delay loop... 1943.56 Zoltan> BogoMIPS Oops: timer tick before it's due Zoltan> (itc=97c85f8eed,itm=97c87b85d7) Oops: timer tick before it's Zoltan> due (itc=97c8d4a7c7,itm=97c8dc1d93) Oops: timer tick before Zoltan> it's due (itc=97c949bc39,itm=97c95006db) Zoltan> Once it is over, everything seems to be correct. E.g. I can Zoltan> stress the system by compiling the kernel with "make -j100". Zoltan> It's a 2.6.5 kernel. I forgot to mention: make sure you have Bjorn's patch in your tree: Stable cset id: davidm@tiger.hpl.hp.com|ChangeSet|20040513223146|25847 ChangeSet@1.1608.9.11, 2004-05-13 15:31:46-07:00, davidm@tiger.hpl.hp.com ia64: fix spurious "timer tick before it's due" problem Patch Bjorn Helgaas: Fix the "timer tick before it's due" complaint from timer_interrupt(). The problem was that smp_callin() turned on the periodic timer tick before syncing the ITC with the BP. This went in _after_ 2.6.6 so it's likely that this will fix your problem (I never saw the issue on a 4-way, though). --david