Re: [PATCH] percpu-refcount: Use normal instead of RCU-sched"

From: Dennis Zhou
Date: Thu Nov 07 2019 - 11:55:25 EST


On Thu, Nov 07, 2019 at 05:28:42PM +0100, Sebastian Andrzej Siewior wrote:
> On 2019-11-07 11:17:49 [-0500], Dennis Zhou wrote:
> > Hello,
>
> Hi,
>
> > I just want to clarify a little bit. Is this patch aimed at fixing an
> > issue with RT kernels specifically?
>
> Due to the implications of preempt_disable() on RT kernels it fixes
> problems with RT kernels.
>

Great, do you mind adding this explanation with what the implications
are in the commit message?


> > It'd also be nice to have the
> > numbers as well as if the kernel was RT or non-RT.
>
> The benchmark was done on a CONFIG_PREEMPT kernel. As said in the commit
> log, the numbers were mostly the same, I can re-run the test and post
> numbers if you want them.
> This patch makes no difference on PREEMPT_NONE or PREEMPT_VOLUNTARY
> kernels.
>

I think a more explicit explanation in the commit message would suffice.

Thanks,
Dennis