[concurrency-interest] Array allocation and access on the JVM

Ismael Juma mlists at juma.me.uk
Fri Jan 27 12:41:48 EST 2012


On Fri, Jan 27, 2012 at 5:12 PM, Doug Lea <dl at cs.oswego.edu> wrote:

> I see a 0-4% slowdown (depending on exact processor/platform)
> in non-concurrent programs on multisocket (multiprocesssor)
> machines when -XX:+UseCondCardMark is used.


> But I routinely see complete failure to speed up (so, a slowdown as
> large as the number of processors you have) in parallel programs
> when -XX:+UseCondCardMark is not used.
>
> The obvious heuristic is to turn it on by default if on
> a multisocket machine.


Thanks for the information Doug. Seems obvious indeed.

Best,
Ismael
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