[concurrency-interest] Fences and card tables

Andrew Haley aph at redhat.com
Sun Aug 23 04:58:36 EDT 2015


On 08/21/2015 02:16 PM, Doug Lea wrote:
> On 08/20/2015 01:50 PM, Andrew Haley wrote:
>> Just to reassure me: a card table write in a generational collector
>> only needs a StoreStore fence, not a release.  Is that right?
>>
> 
> Definitive answers might be collector-specific.
> So you might try asking on hotspot-gc-dev?
>    http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-dev

Sure, I understand that.  My question was more general, following
Hans's sometimes surprising observations of the failures of StoreStore
fences.  A card table store is merely a constant written into a table,
and that constant is fixed.  All that is required is that the
preceding reference store and the card table store are observable to
all threads in the order they were written.  Hence a StoreStore fence.

Andrew.


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