Unsafe.{get,put}-X-Unaligned performance (original) (raw)

John Rose john.r.rose at oracle.com
Wed Mar 11 07:10:04 UTC 2015

On Mar 10, 2015, at 12:02 PM, Andrew Haley <aph at redhat.com> wrote:

The new algorithm is slightly slower because of branch misprediction. old: 2.17 IPC, 0.08% branch-misses, 91,965,281,215 cycles new: 1.23 IPC, 6.11% branch-misses, 99,925,255,682 cycles ...but it executes fewer instructions so we're only talking about some 10% slowdown. I think this is the worst case (or something close to the worst case) for the new algorithm. So, I think we're OK performance-wise.

I agree.

John: I'm waiting for an answer to my question here before I submit a webrev for approval. http://mail.openjdk.java.net/pipermail/panama-dev/2015-March/000099.html <http://mail.openjdk.java.net/pipermail/panama-dev/2015-March/000099.html>

(Answered.)

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