RFR: 8152955: Many safepoints of "no vm operation" kind

[David Holmes]

Hi Robbin,

On 24/05/2017 4:32 AM, Robbin Ehn wrote:
> Hi all, please review.
> 
> When cleanup, safepointalot or vm halt starts a safepoint without an 
> operation we now set a reason string for.
> 
> Webrev: http://cr.openjdk.java.net/~rehn/8152955/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8152955

This looks good. A couple of minor comments:

+ bool VMThread::no_op_safepoint_needed(bool check_time) {
+   _no_op_reason = "no operation"; // This value should never be printed

Not sure why you set "no operation". Harmless but ...

396     bool max_time_exceeded = GuaranteedSafepointInterval != 0 && 
(interval > GuaranteedSafepointInterval);

Can you split into two lines please.

No need to see update, whatever you choose to do.

Thanks,
David

> Passes hotspot_tier1
> 
> Thanks, Robbin