review for 7029167: add support for conditional card marks

[Igor Veresov]

On 3/30/11 5:33 PM, Tom Rodriguez wrote:
>
> On Mar 30, 2011, at 5:25 PM, Igor Veresov wrote:
>
>> Looks good.
>
> Thanks!
>
>> 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.
>

May be a comment then, saying that ConI(0) represents dirty_card ? Just 
for the sake of future grepping?

igor

> tom
>
>>
>>
>> igor
>>
>> On 3/30/11 4:46 PM, Tom Rodriguez wrote:
>>> http://cr.openjdk.java.net/~never/7029167
>>>
>>> 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.
>>>
>>
>