review for 7029167: add support for conditional card marks

Tom Rodriguez tom.rodriguez at
Wed Mar 30 17:33:03 PDT 2011

On Mar 30, 2011, at 5:25 PM, Igor Veresov wrote:

> Looks good.


> Could you use CardTableModRefBS::dirty_card_val() instead of 0? I know we use just zero already in many places, but I'm fresh from barrier experimentation and it would've been much nicer if we used symbolic names.

I'd rather not.  If we really want to use dirty_card_val then it should be done everywhere as its own change instead of just patching part of C2.


> igor
> On 3/30/11 4:46 PM, Tom Rodriguez wrote:
>> 7029167: add support for conditional card marks
>> Reviewed-by:
>> Repeated updates to the card table can be a source of contention on
>> multiprocessor machines that can greatly inhibit scalability.  This
>> adds support in C2 for conditional card marks.  Tested with jbb and
>> CTW.  At some point this should be turned on automatically when multi
>> socket machines are detected but that's covered under another bug as
>> is C1 support.

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