RFR(s): 8150362: G1 base elapsed time prediction is wrong because rs_length prediction is wrong

sangheon sangheon.kim at oracle.com
Wed Mar 9 19:48:48 UTC 2016


Hi Thomas,

Thanks for reviewing this.

Sangheon


On 03/09/2016 01:23 AM, Thomas Schatzl wrote:
> Hi Sangheon,
>
> On Tue, 2016-03-08 at 10:08 -0800, sangheon wrote:
>> Hi all,
>>
>> Could I have some reviews for this change?
>>
>> We predict remembered set length as follows from
>> G1CollectorPolicy::predict_base_elapsed_time_ms(size_t
>> pending_cards):
>> size_t rs_length = predict_rs_length_diff();
>>
>> This is incomplete and it is inconsistent when compare with the use
>> case
>> of the function from
>> G1CollectorPolicy::calculate_young_list_target_length().
>> 'adj_rs_lengths = rs_lengths + predict_rs_length_diff()'
>> In this case, we use rs_length + rs_length_diff.
>>
>> I am proposing to use the sum of rs_length and rs_length_diff.
>> i.e. 'rs length + rs length diff'.
>>
>> CR: https://bugs.openjdk.java.net/browse/JDK-8150362
>> Webrev: http://cr.openjdk.java.net/~sangheki/8150362/webrev.00
>> Testing: JPRT, some performance tests showed no big difference.
>   looks good.
>
> Thanks,
>    Thomas
>
>



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