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

Mikael Gerdin mikael.gerdin at oracle.com
Wed Mar 9 08:52:03 UTC 2016


Hi Sangehon,

On 2016-03-08 19:08, 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

Looks good.

/Mikael

> Testing: JPRT, some performance tests showed no big difference.
>
> Thanks,
> Sangheon


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