On 2014年07月23日 18:53, Pavel Machek wrote: > Hi! > >> In the current world, all nonboot cpus are enabled serially during system >> resume. System resume sequence is that boot cpu enables nonboot cpu one by >> one and then resume devices. Before resuming devices, there are few tasks >> assigned to nonboot cpus after they are brought up. This waste cpu usage. >> >> To accelerate S3, this patches adds a new kernel configure >> PM_PARALLEL_CPU_UP_FOR_SUSPEND to allow boot cpu to go forward to resume >> devices after bringing up one nonboot cpu. The nonboot cpu will be in charge >> of bringing up other cpus. This makes enabling cpu2~x parallel with resuming >> devices. From the test result on 4 logical core laptop, the time of resume >> device almost wasn't affected by enabling nonboot cpus lately while the start >> point is almost 30ms earlier than before. > > Does this mean that userspace can now run seeing the "offlined" cpus > still in offline state?
No, the PM event handler of cpu hotplug will reenable cpu hotplug via cpu_hotplug_enable() at the end of system resume. The function will wait for currently running cpu hotplug operations to complete. > > Pavel > -- Best regards Tianyu Lan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
