Re: [PATCH/RFC] NFS: state manager thread must start running.

[Tejun Heo <tj@kernel.org>]

Hello, Neil.

On Tue, Jul 15, 2014 at 06:13:17PM +1000, NeilBrown wrote:
> Could do that (or per-client) but it doesn't really buy us anything does it?

It does buy some.

1. The kworker threads are more likely to be cache-hot than explicit
   kthreads.

2. Workqueue is a lot eaiser to get right in terms of synchronization
   and freezing.

3. Workqueue mandates well-defined boundaries between separate
   execution instances which often makes it a lot easier to implement
   and update kernel-wide features such as like freezer and runtime
   kernel patching.

> The state manager assumes it is single threads, so it would need to be
> a single-threaded workqueue with always at least one thread running.
> That is much the same as a kthread.
> 
> And then there is that fact that the current code explicitly enabled SIGKILL
> and maybe that is important.

If SIGKILL handling is mandatory (really?), kthread_worker can be used
for #2 and #3.

Thanks.

-- 
tejun