Fwd: GC Help

[Andrew Haley]

On 24/10/17 07:24, amith pawar wrote:
> Is it good to have bulk zeroing feature/pass in GC where once sweeping is
> done then do bulk zero ? If this is done then during allocation step
> zeroing is not required as it is done in GC itself.
> 
> Not sure how much time GC will take for this.
> 
> I may not be the first person to think this way and thought to ask here.
> Does JAVA spec allows this (such pass in GC)? if so any pointers on that.
> It will help me to understand more.

It's called -XX:+ZeroTLAB.  See also ReduceBulkZeroing.

It may or may not be effective: zeroing at allocation time is fairly
cache friendly, whereas zeroing when allocating a new TLAB isn't going
to be.  Some architectures have cache-missing bulk zeroing, which
might help.

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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