Spin Loop Hint support: Draft JEP proposal (original) (raw)

Andrew Haley aph at redhat.com
Mon Oct 5 09:41:52 UTC 2015

Hi Gil,

On 04/10/15 17:22, Gil Tene wrote:

Summary

Add an API that would allow Java code to hint that a spin loop is being executed.

I don't think this will work for ARM, which has a rather different spinlock mechanism.

Instead of PAUSE, we wait on a lock word with WFE. WFE puts a core into a lightweight sleep state waiting on a particular address (the lock word) and a write to the lock word wakes it up. This is very useful and somewhat analogous to 86's MONITOR/MWAIT.

I can't immediately see how to generalize your proposal to ARM, which is a shame.

Andrew.

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