Re: [PATCH v2 7/7] driver-core: add preferred async probe option for built-in and modules

Luis R. Rodriguez
2014-10-07T18:55:39Z

On Tue, Oct 7, 2014 at 10:55 AM, Tejun Heo <tj@kernel.org> wrote:
> Hello,
>
> On Tue, Oct 07, 2014 at 07:50:10PM +0200, Luis R. Rodriguez wrote:
>> On Tue, Oct 07, 2014 at 01:34:04PM -0400, Tejun Heo wrote:
>> > But you can create a new workqueue and queue all the async probing
>> > work items there and flush the workqueue right after
>> > async_synchronize_full().
>>
>> On second thought I would prefer to avoid this, I see this being good
>> to help with old userspace but other than that I don't see a requirement
>> for new userspace. Do you?
>
> Hmmm... we batch up and do everything parallel, so I'm not sure how
> much gain we'd be looking at by not waiting for at the end before
> jumping into the userland. Also, it's a bit of an orthogonal issue.
> If we wanna skip such synchornization point before passing control to
> userland, why are we applying that to this but not
> async_synchronize_full() which has a far larger impact? It's weird to
> synchronize one while not the other, so yeah, if there are actual
> benefits we can consider it but let's do it separately.

OK I'll just kill bus.enable_kern_async=1 to enable built-in async
probe support *and* also have prefer_async_probe *always* be
respected, whether modular or not.

Luis