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On Sun, Mar 23, 2008 at 04:54:29PM +0100, Peter Zijlstra wrote: > On Sun, 2008-03-23 at 16:44 +0100, Marcin Slusarz wrote: > > On Sun, Mar 02, 2008 at 08:58:37PM +0100, Peter Zijlstra wrote: > > > > > > On Sun, 2008-03-02 at 20:47 +0100, Marcin Slusarz wrote: > > > > On Sun, Mar 02, 2008 at 08:11:11PM +0100, Peter Zijlstra wrote: > > > > > > > > > > On Sun, 2008-03-02 at 20:00 +0100, Marcin Slusarz wrote: > > > > > > Hi > > > > > > Since early 2.6.25 days I'm having strange lockup on boot. As it happens > > > > > > rarely (in ~10% of boots), I couldn't bisect it. No kernel panic, SysRq > > > > > > didn't work, so I couldn't provide any useful informations to LK community. > > > > > > I hoped someone else would fix it... :) > > > > > > > > > > > > It's rc3 so I decided to narrow it down myself. I enabled netconsole > > > > > > to see whether some other informations are printed before lockup. > > > > > > It didn't help, but I noticed that lockup happens much more frequenly! (~50%) > > > > > > So I bisected it down to: > > > > > > > > > > > > 8f4d37ec073c17e2d4aa8851df5837d798606d6f is first bad commit > > > > > > commit 8f4d37ec073c17e2d4aa8851df5837d798606d6f > > > > > > Author: Peter Zijlstra <a.p.zijlstra@chello.nl> > > > > > > Date: Fri Jan 25 21:08:29 2008 +0100 > > > > > > > > > > > > sched: high-res preemption tick > > > > > > > > > > > > Use HR-timers (when available) to deliver an accurate preemption tick. > > > > > > > > > > > > The regular scheduler tick that runs at 1/HZ can be too coarse when nice > > > > > > level are used. The fairness system will still keep the cpu utilisation 'fair' > > > > > > by then delaying the task that got an excessive amount of CPU time but try to > > > > > > minimize this by delivering preemption points spot-on. > > > > > > > > > > > > The average frequency of this extra interrupt is sched_latency / nr_latency. > > > > > > Which need not be higher than 1/HZ, its just that the distribution within the > > > > > > sched_latency period is important. > > > > > > > > > > > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> > > > > > > Signed-off-by: Ingo Molnar <mingo@elte.hu> > > > > > > > > > > > > :040000 040000 ab225228500f7a19d5ad20ca12ca3fc8ff5f5ad1 f1742e1d225a72aecea9d6961ed989b5943d31d8 M arch > > > > > > :040000 040000 25d85e4ef7a71b0cc76801a2526ebeb4dce180fe ae61510186b4fad708ef0211ac169decba16d4e5 M include > > > > > > :040000 040000 9247cec7dd506c648ac027c17e5a07145aa41b26 950832cc1dc4d30923f593ecec883a06b45d62e9 M kernel > > > > > > > > > > > > I can't revert it on top of rc3 because of conflicts. > > > > > > > > > > This should do, I guess. Weird though, I haven't had trouble with this > > > > > patch in a long long while. Nor I suppose has Ingo's QA setup. > > > > Ok. It did the trick. But it's temporary fix, right? > > > > > > Yeah, for a proper fix I'd need to understand what goes wrong.. and that > > > requires I get more information. Hopefully I can reproduce your issue. > > > > > > > > Will try if I can reproduce using your .config. > > > > I think this lockup might depend on use of dhcp and/or parallel > > > > starting of services... > > > > > > It _should_ not.. :-) I can try dhcp quite easily, if nothing comes up I > > > can try installing gentoo on a test box, stage3 installs are easy > > > enough. > > > > I'm still having this lockup on 2.6.25-rc6 (028011e1391eab27e7bc113c2ac08d4f55584a75). > > What informations do you need? > > Does the NMI watchdog (append nmi_watchdog=2) report anything? > > I've never been able to reproduce myself :-/ 4 different lockups: http://alan.umcs.lublin.pl/~mslusarz/kernel/2008.03.23-lockup/ Are there any downsides of using nmi_watchdog=2 all the time? ps: Documentation/nmi_watchdog.txt says: "Currently, local APIC mode (nmi_watchdog=2) does not work on x86-64.". It's not true, so maybe someone should update this file? | ||||||||||
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