CONFIG_RT_GROUP_SCHED

[Colin Ian King]

On 27/07/2021 19:57, Tim Gardner wrote:
> Does anyone have experience with this config option ? 

I did some analysis a while ago (31st March 2020) and Cc'd Francis and
Seth on the results. Here is what I wrote:

"I ran some synthetic stress-ng throughput and latency tests with and
without CONFIG_RT_GROUP_SCHED on CONFIG_RT_GROUP_SCHED.  I don't see
enough variation in the throughput or latency to warrant any concern
about enabling this option.  We have quite a bit of small jitter on the
results, but overall the kernel results are similar enough to make me
feel OK to enable this option for Focal.

Attached is a LibreOffice spread sheet with my results.  I didn't run
the LKP tests as these take ~15 hours per run to complete and I don't
think it will give us much more useful information."

See attachment.

Colin

>It is my
> impression that without allocating any RT threads that there is no
> change in default behavior. A brief survey of code enabled by
> CONFIG_RT_GROUP_SCHED _kind_ of reinforces that observation.  The reason
> I ask is that Microsoft has been testing this config option with the
> Azure kernel. It has satisfied at least one customer that wanted this
> option. They (MSFT) plan to test to make sure its really doing what they
> want as well as watching for behavioral changes or regressions. I
> thought adding any information from y'all would be helpful.
> 
> rtg

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