Messages in this thread | | | Subject | Re: [PATCH v5 4/4] x86: initialize secondary CPU only if master CPU will wait for it | From | Toshi Kani <> | Date | Mon, 05 May 2014 15:35:10 -0600 |
| |
On Mon, 2014-05-05 at 22:49 +0200, Igor Mammedov wrote: > Hang is observed on virtual machines during CPU hotplug, > especially in big guests with many CPUs. (It reproducible > more often if host is over-committed). > > It happens because master CPU gives up waiting on > secondary CPU and allows it to run wild. As result > AP causes locking or crashing system. For example > as described here: https://lkml.org/lkml/2014/3/6/257 > > If master CPU have sent STARTUP IPI successfully, > and AP signalled to master CPU that it's ready > to start initialization, make master CPU wait > indefinitely till AP is onlined. > To ensure that AP won't ever run wild, make it > wait at early startup till master CPU confirms its > intention to wait for AP. If AP doesn't respond in 10 > seconds, the master CPU will timeout and cancel > AP onlining. > > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Thanks for the update.
Acked-by: Toshi Kani <toshi.kani@hp.com>
-Toshi
| |