Messages in this thread | | | Date | Thu, 2 Dec 2010 11:15:02 -0500 | From | Don Zickus <> | Subject | Re: perf hw in kexeced kernel broken in tip |
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On Thu, Dec 02, 2010 at 08:34:30AM +0100, Peter Zijlstra wrote: > 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. > > > 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.
Ok, I moved the reboot notifier stuff from kernel/watchdog.c to kernel/perf_event.c. Things still worked fine from a kexec perspective.
Vivek suggested to me this morning that I should just blantantly disable the perf counter during init when running my test. Looking through the code I don't think I can do this using disable_all because some routines look for the active bit to be set and some arches have different disable registers than others. Thoughts?
Cheers, Don
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