RFR(XL): 8185640: Thread-local handshakes

Robbin Ehn robbin.ehn at oracle.com
Mon Oct 30 14:34:29 UTC 2017


There have been a bit hesitation and confusion about the option (at least 
The option is opt-out but in globals.hpp it starts out as false.

Now instead we explicit set it true in globals.hpp but we turn it off if we 
notice that:
- We are on an unsupported platform
- User have specified UseAOT
- User have specified EnableJVMCI

Here is webrev for changes needed:
And here is CSR:

Manual testing + basic testing done.

And since I'm really hoping that this can be the last incremental, here is my 
whole patch queue flatten out:

Thanks, Robbin

On 10/27/2017 04:47 PM, Doerr, Martin wrote:
> Hi Robbin,
> excellent. I think this matches what Coleen had proposed, now.
> Thanks for doing all the work with so many incremental patches and for responding on so many discussions. Seems to be a tough piece of work.
> Best regards,
> Martin
> -----Original Message-----
> From: Robbin Ehn [mailto:robbin.ehn at oracle.com]
> Sent: Freitag, 27. Oktober 2017 15:15
> To: Erik Österlund <erik.osterlund at oracle.com>; Andrew Haley <aph at redhat.com>; Doerr, Martin <martin.doerr at sap.com>; Karen Kinnear <karen.kinnear at oracle.com>; Coleen Phillimore (coleen.phillimore at oracle.com) <coleen.phillimore at oracle.com>
> Cc: hotspot-dev developers <hotspot-dev at openjdk.java.net>
> Subject: Re: RFR(XL): 8185640: Thread-local handshakes
> Hi all,
> Poll in switches:
> http://cr.openjdk.java.net/~rehn/8185640/v7/Interpreter-Poll-Switch-10/
> Poll in return:
> http://cr.openjdk.java.net/~rehn/8185640/v7/Interpreter-Poll-Ret-11/
> Please take an extra look at poll in return.
> Sanity tested, big test run still running (99% complete - OK).
> Performance regression for the added polls increased to total of -0.68% vs
> global poll. (was -0.44%)
> We are discussing the opt-out option, the newest suggestion is to make it
> diagnostic. Opinions?
> For anyone applying these patches, the number 9 patch changes the option from
> product. I have not sent that out.
> Thanks, Robbin

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