Loop strip mining to decreases safepoint poll frequency

[Aleksey Shipilev]

Very cool.

This affects only counted loops too, right?

On 02/28/2017 11:23 AM, Roland Westrelin wrote:
> +UseCountedLoopSafepoints is another way to disable it (and it then runs with
> a safepoint per loop iteration).

I don't get this part.

I would expect -XX:+UseCLS and -XX:LSM=# to be independent. That is, behave like
this:

  a) -XX:+UseCLS -XX:LSM=0:
    what we have now; counted loops with safepoints

  b) -XX:-UseCLS -XX:LSM=0:
   no safepoints in counted loops -- strip mining is useless?

  c) -XX:+UseCLS -XX:LSM=<positive>:
   strip-mined counted loops with safepoints

  d) -XX:-UseCLS -XX:LSM=<positive>:
   no safepoints in counted loops -- strip mining is useless?

My concern is that latency-oriented people do run with -XX:+UseCLS in their
configurations, and current patch seems to disable loop strip mining for them!

Thanks,
-Aleksey