On Wed, 14 Dec 2011, Avi Kivity wrote: > On 12/08/2011 05:19 PM, Eric B Munson wrote: > > > error compiling committee.c: too many arguments to function > > > > > My concern for preempt notifiers is masking real soft lockup warnings. If the > > flag is set every time the vm is preempted, it becomes more likely that we will > > mask real warnings. The ioctl was choosen because it sets the flag only when > > the guest is being paused deliberately. > > > > AFAIK, SIGSTOP is not a supported way to stop a qemu vm so a soft lockup > > This is a kvm patch, not a qemu patch. In general we try to address > general requirements, not just those that are specific to one userspace, > even if it is near to our hearts. > > > warning would be working as designed there. If that isn't the case, or if it > > ever changes, we could always install a signal handler for SIGCONT that set the > > flag before resuming the vm. > > > > Scheduling delays are also beyond the scope of this problem and I see the soft > > lockup warning as appropriate in that case. > > I don't think you should see a guest softlockup if the host is > overloaded. Nor should you see it due to a long live migration pause, > or STOP/CONT. You should see a guest softlockup if it is spinning due > to a guest bug, and not for any other reason. > > I think we need a mix of the ioctl (for STOP/CONT and voluntary pauses, > like live migration or qemu stop/cont) and preempt notifiers (together > with a check for TASK_RUNNING/TASK_UNINTERRUPTIBLE, for scheduling or > swap delays) > > -- > error compiling committee.c: too many arguments to function > Do you want the preemption notifier work in before you will consider merging this set, or can that be a follow on? Eric
Attachment:
signature.asc
Description: Digital signature
