* Jiri Kosina <jkosina@xxxxxxx> wrote: > On Sat, 21 Feb 2015, Ingo Molnar wrote: > > > (It does have some other requirements, such as making > > all syscalls interruptible to a 'special' signalling > > method that only live patching triggers - even syscalls > > that are under the normal ABI uninterruptible, such as > > sys_sync().) > > BTW I didn't really understand this -- could you please > elaborate what exactly do you propose to do here in your > "simplified" patching method (i.e. serializing everybody > at the kernel boundary) for TASK_UNINTERRUPTIBLE > processess? So I'd try to separate out the two main categories of uninterruptible sleepers: - those who just serialize with other local CPUs/tasks relatively quickly - those who are waiting for some potentially very long and open ended request. [such as IO, potentially network IO.] I'd only touch the latter: a prominent example would be sys_sync(). I'd leave alone the myriads of other uninterruptible sleepers. > But I didn't understand your claims regarding > uninterruptible sleeps in your paragraph above. > sys_sync() is one thing, that's just waiting > uninterruptibly for completion. But how about all the > mutex waitiers in TASK_UNINTERRUPTIBLE, for example? I'd not touch those - unless they are waiting for something that will not be done by the time we park all tasks: for example NFS might have uninterruptible sleeps, and sys_sync() will potentially do IO for minutes. I think it would be the exception, not the rule - but it would give us an approach that allows us to touch 'any' kernel code if its wait times are unreasonably long or open ended. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
