Messages in this thread | | | Subject | Re: perf hw in kexeced kernel broken in tip | From | Peter Zijlstra <> | Date | Thu, 02 Dec 2010 08:34:30 +0100 |
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On Thu, 2010-12-02 at 00:23 -0500, Don Zickus wrote: > On Wed, Dec 01, 2010 at 01:48:07PM -0800, Eric W. Biederman wrote: > > > > > > Oh, but I'm not a device or sysdev thing, I'll never get something like > > > that. > > > > There is also the reboot notifier, if the NMI needs to be controlled > > outside of device model. Sigh. The NMI handling is such a special case. > > I tried reboot notifiers with the nmi_watchdog and acheived some success > (on a Westmere box, a P4 still failed). Kdump is still screwed, but maybe > we don't care for now. > > Here is the quick and dirty patch I used.
> diff --git a/kernel/watchdog.c b/kernel/watchdog.c > index 792a4ed..3455cf9 100644 > --- a/kernel/watchdog.c > +++ b/kernel/watchdog.c > @@ -23,6 +23,7 @@ > #include <linux/notifier.h> > #include <linux/module.h> > #include <linux/sysctl.h> > +#include <linux/reboot.h> > > #include <asm/irq_regs.h> > #include <linux/perf_event.h> > @@ -550,6 +551,18 @@ static struct notifier_block __cpuinitdata cpu_nfb = { > .notifier_call = cpu_callback > }; > > +static int __cpuinit > +reboot_callback(struct notifier_block *nfb, unsigned long action, void *unused) > +{ > + watchdog_disable_all_cpus(); > + > + return notifier_from_errno(0); > +} > + > +static struct notifier_block __cpuinitdata reboot_nfb = { > + .notifier_call = reboot_callback > +}; > + > void __init lockup_detector_init(void) > { > void *cpu = (void *)(long)smp_processor_id(); > @@ -563,6 +576,7 @@ void __init lockup_detector_init(void) > > cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); > register_cpu_notifier(&cpu_nfb); > + register_reboot_notifier(&reboot_nfb); > > return; > }
We'd really want a perf_event.c callback there to do as the hot-unplug code does and detach all running counters from the cpu.
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