On Friday 20 April 2012 06:35 PM, Thomas Gleixner wrote: > Dear all, > > I'm working on refactoring the SMP boot and CPU hotplug implementation. > > The current code has evolved over time into a conglomerate of > warts. My main goals are to: > > - reduce the architecture code by moving repeating constructs to the > core > > - redesigning the handling of per cpu threads. There is no point to > tear down the threads just to create them again. > > - restructuring the notifier facility into a proper tree with > dependencies to avoid the gazillion of callbacks and moving > setup/teardown code into the context of the upcoming/dying cpu > > The motivation behind this work is the cpu hotplug nightmare which we > are facing in the RT kernel and the requests from several groups > (e.g. ARM) to make hotplug more lightweight and faster. > > This first part moves the idle thread management for non-boot cpus > into the core. fork_idle() is called in a workqueue as it is > implemented in a few architectures already. This is necessary when not > all cpus are brought up by the early boot code as otherwise we would > take a ref on the user task VM of the thread which brings the cpu up > via the sysfs interface. > > This converts all architectures except m32r, mn10300, tile and UM to > the new core facility. These architecture are calling fork_idle() in > the very early boot code in smp_prepare_cpus() for unknown reasons. > I haven't analyzed yet, whether this is on purpose or can be moved > over to the generic facility. It'd be nice if the responsible maintainers > could look into that as well. > Tried this series on OMAP4 (Dual Core ARM machine) and did some some testing with CPU hot-plug by creating variable CPU loads and running CPU hot-plug script in the background. No issue observed in 2 hours of testing. Not sure your stand on Suresh's patch[1], but I did another round of testing with [1] included. I thought this patch might be considered since it eliminate the need for work-queue based idle thread allocation which can be a problem as discussed on this thread. Regards Santosh [1] https://lkml.org/lkml/2012/4/20/524 -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
