Workqueue scheduling policy

Workqueue scheduling policy

[spdev31]

Hi,

I see the workqueue scheduling policys defaults to SCHED_FIFO with the
2.6.33 RT patch but is SCHED_NORMAL with the 3.0 RT patch (and newer
RT patches, I believe).  Can you help me understand the reason for
using realtime policies for 2.6.33 RT workqueues and non-realtime
policies for 3.0 RT patch workqueues?

Thanks,
Shaun

Re: Workqueue scheduling policy

[Steven Rostedt]

On Thu, 15 Aug 2013 13:59:49 -0700
spdev31 <spdev31@gmail.com> wrote:

> Hi,
> 
> I see the workqueue scheduling policys defaults to SCHED_FIFO with the
> 2.6.33 RT patch but is SCHED_NORMAL with the 3.0 RT patch (and newer
> RT patches, I believe).  Can you help me understand the reason for
> using realtime policies for 2.6.33 RT workqueues and non-realtime
> policies for 3.0 RT patch workqueues?
> 

Actually, mainline kernel set workqueues as SCHED_FIFO for 2.6.33 and
no longer does that for 3.0 kernels. Has nothing to do with the -rt
patch.

But as for why they did that switch. Probably because there's no reason
that the workqueues need to be running as a high priority task, just
like ksoftirqd runs as SCHED_OTHER in mainline.

-- Steve