RFR (M): 8188764: Obsolete AssumeMP and then remove all support for non-MP builds

David Holmes david.holmes at oracle.com
Tue Sep 18 07:04:39 UTC 2018

On 18/09/2018 4:37 PM, Doerr, Martin wrote:
> Hi David,
>> It is still used for spin-loop and related optimisations. Badly tuned
>> spinloops on uniprocessors could be a significant performance issue.
>> Keeping the is_MP check on a MP system is no hindrance as its just part
>> of the spin-loop.
> So this means you're actually fixing this.
> os::is_MP is always true in the current implementation (due to "AssumeMP ||").

Out-of-the-box yes. I'm assuming anyone actually running on a 
uniprocessor would have set -XX:-AssumeMP.


> Thanks for explaining.
> Shared code part looks fine.
> Thanks,
> Martin

More information about the hotspot-dev mailing list