Time to Safepoint and HotSpot intrinsics

Andrew Haley aph at redhat.com
Tue Nov 27 10:41:31 UTC 2018

On 11/26/18 10:01 PM, Hohensee, Paul wrote:
> The compiler could estimate the cost of an iteration using some rough pessimistic heuristic and strip mine based on that.

But the compiler doesn't see the intrinsics: they are hand-coded assembly

> Measuring the safepoint time directly is fragile due to inability to find all the hardware platforms that might run the JVM. A671

Sure, but all I'm suggesting is that we take an order-of-magnitude guess
and apply that to our intrinsics. It does not have to be accurate: in the
case of encryption the speed difference caused by limiting the number of
iterations is infinitesimal, but the time to safepoint difference is huge.

IMO, this is a true no brainer.

Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671

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