Messages in this thread | | | Date | Thu, 7 Nov 2019 18:24:34 +0100 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH] percpu-refcount: Use normal instead of RCU-sched" |
| |
On 2019-11-07 11:55:19 [-0500], Dennis Zhou wrote: > On Thu, Nov 07, 2019 at 05:28:42PM +0100, Sebastian Andrzej Siewior wrote: > > > 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?
some RCU section here invoke callbacks which acquire spinlock_t locks. This does not work on RT with disabled preemption.
> > > 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.
What do you mean by "more explicit explanation"? The part with the numbers or that it makes no difference for PREEMPT_NONE and PREEMPT_VOLUNTARY?
> Thanks, > Dennis
Sebastian
| |