On Mon, Aug 18, 2014 at 08:07:35PM +0200, Ingo Molnar wrote: > > * Don Zickus <dzickus@xxxxxxxxxx> wrote: > > > On Mon, Aug 18, 2014 at 11:16:44AM +0200, Ingo Molnar wrote: > > > > > > * Don Zickus <dzickus@xxxxxxxxxx> wrote: > > > > > > > The running kernel still has the ability to enable/disable at any > > > > time with /proc/sys/kernel/nmi_watchdog us usual. However even > > > > when the default has been overridden /proc/sys/kernel/nmi_watchdog > > > > will initially show '1'. To truly turn it on one must disable/enable > > > > it, i.e. > > > > echo 0 > /proc/sys/kernel/nmi_watchdog > > > > echo 1 > /proc/sys/kernel/nmi_watchdog > > > > > > This looks like a bug, why is this so? > > > > It is, but it always has been there in the case of the PMU > > not being able to provide a resource for the hardlockup. > > This change just exposes it more. > > There seems to be two issues: > > 1) > > When it's impossible to enable the hardlockup detector, it > should default to -1 or so, and attempts to set it should > return a -EINVAL or so. Ok, it didn't because I set the knob to mean both hard and soft lockup. But the code knows the failures and can set to -1 if it had to. > > Bootup messages should also indicate when it's not possible to > enable it but a user requests it. It does today. > > 2) > > The softlockup and hardlockup detection control variables > should be in separate flags, inside and outside the kernel - > they (should) not relate to each other. They did because years ago I thought we wanted to keep them as one entity instead of two. I would have to re-work the code to do this (and add more knobs). I presume you would want those changes done before taking this patchset? Cheers, Don -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
