Hi Gil, Glad to see this being addressed!
On 10/04/2015 07:22 PM, Gil Tene wrote: > We propose to add a method to the JDK which would be hint that a spin > loop is being performed. E.g. > jdk.util.PerformanceHints.spinLoopHint(), which will hopefully evolve > to a Java SE API, e.g. java.util.PerformanceHints.spinLoopHint(). The > specific name space location, class name, and method name will be > determined as part of development of this JEP. Yes, that would be a tough part. JDK is usually oblivious of these low-level platform-specific hints, they go to sun.misc.* (e.g. Unsafe, @Contended and others...). I'll let Project Leads to make that call :) > [4] HotSpot WebRevs for prototype implementation which intrinsifies > org.performancehintsSpinHint.spinLoopHint() > http://ivankrylov.github.io/spinloophint/webrev/ > <http://ivankrylov.github.io/spinloophint/webrev/> * product_pd (platform-dependent) flags can be used to conditionalize the support on a platform. This helps to avoid vm_version_* tricks. * Does spinloophint imply membar as well? x86_64.ad suggests so. library_call.cpp suggests so. It seems weird to conflate the two, even though it's understandable you want to piggyback on existing machinery. * I think spinLoopHint() misses a @HotspotIntrinsicCandidate annotation. Thanks, -Aleksey
