Gregory Haskins wrote: > On Wed, 2007-07-25 at 06:20 +0300, Avi Kivity wrote: > > >> I'd rather wait for the real fix, especially as this is an experimental >> branch. Can you provide details of the issue? >> >> > > Sure. Keep in mind I am working with the RT kernel, so things might be > tighter and/or different than the vanilla kernel w.r.t. what I am about > to say: > > But in a nutshell, the current code calls vcpu_clear() during a sched-in > operation. If the vcpu is simply uninitialized, no problem. We clear > it inline in the handler. However, if the vcpu is migrating we have an > issue. A synchronous smp_call_function_single() is invoked to > vcpu_clear the remote pCPU, but you must have interrupts enabled to call > this function to avoid a deadlock in the IPI handshake. sched-in() > handlers are (and should be) called with interrupts and preemption > disabled. > >
Preemption disabled yes, but interrupts? IIRC I picked the place where sched_in is called to have interrupts enabled, but maybe -rt changes that. Seems like finding a better position for that hook would solve the problem. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
