RFR: 7169803: Usage of pretenured value is not correct
David Lindholm
david.lindholm at oracle.com
Thu Jun 11 08:17:26 UTC 2015
Hi,
This is also my impression.
tenured_allocation(size_t size) is called from PSOldGen::allocate() that
allocates objects directly in the old generation (between collections).
Thanks,
David
On 2015-06-11 09:47, Tao Mao wrote:
> Hi Jon,
>
> The definition is: "Promoted" is objects that are promoted (or
> tenured) during yGC while "PRE-tenured" is objects that are allocated
> directly in old gen. I believe this is so, right?
>
> Thanks.
> Tao Mao
>
>
>
> On Wed, Jun 10, 2015 at 6:48 PM, Jon Masamitsu
> <jon.masamitsu at oracle.com <mailto:jon.masamitsu at oracle.com>> wrote:
>
>
>
> On 6/10/2015 5:51 PM, Tao Mao wrote:
>> I think David's right. Promoted objects and pretenured objects
>> are different guys. This would resolve the second issue in the
>> ticket JDK-7169803.
>
> Tao,
>
> How would you define each?
>
> Jon
>
>
>>
>> Thanks.
>> Tao Mao
>>
>> On Wed, Jun 10, 2015 at 5:08 PM, Jon Masamitsu
>> <jon.masamitsu at oracle.com <mailto:jon.masamitsu at oracle.com>> wrote:
>>
>>
>>
>> On 6/10/2015 1:30 AM, David Lindholm wrote:
>>
>> Jon,
>>
>> Thanks for taking a look at this. No, I don't think this
>> will lead to double counting. This calculation is already
>> there, it is just buggy. Before this patch the code added
>> the total amount of promoted memory this collection with
>> the average size of the pretenured objects, and used this
>> as a sample. Now the code adds the total amount of
>> promoted memory with the total size of the pretenured
>> objects since last collection, and uses this as a sample
>> instead.
>>
>>
>> Aren't "promoted" and
>> "total_pretenured_since_last_promotion()" approximately the same
>> thing? In share/vm/gc/parallel/psScavenge.cpp
>>
>> 489 size_t promoted = old_gen->used_in_bytes() -
>> old_gen_used_before;
>> 490 size_policy->update_averages(_survivor_overflow,
>> survived, promoted);
>>
>> so "promoted" is the change in the old gen between the before
>> and after the
>> young gen collection.
>>
>> "total_pretenured_size_last_promotion()" is
>>
>> 258 void tenured_allocation(size_t size) {
>> 259 _avg_pretenured->sample(size);
>> 260 add_pretenured_since_last_promotion(size)
>>
>>
>> which seems to me to be calculating the same thing (sum of
>> allocations into the old gen).
>>
>> Not so?
>>
>> Jon
>>
>>
>>
>>
>> Thanks,
>> David
>>
>> On 2015-06-09 21:37, Jon Masamitsu wrote:
>>
>> David,
>>
>> http://cr.openjdk.java.net/~david/JDK-7169803/webrev.00/src/share/vm/gc/parallel/psAdaptiveSizePolicy.cpp.frames.html
>> <http://cr.openjdk.java.net/%7Edavid/JDK-7169803/webrev.00/src/share/vm/gc/parallel/psAdaptiveSizePolicy.cpp.frames.html>
>>
>>
>> 1308 avg_promoted()->sample(promoted +
>> total_pretenured_since_last_promotion());
>>
>>
>> Is including both "promoted" and
>> "total_pretenured_since_last_promotion()"
>> double counting?
>>
>> Jon
>>
>> On 06/09/2015 02:06 AM, David Lindholm wrote:
>>
>> Hi,
>>
>> Please review this patch that corrects the usage
>> of the pretenured value. There were 2 issues:
>> words and bytes were mixed up and the addition
>> was done with the wrong value. See bug for details.
>>
>> Webrev:
>> http://cr.openjdk.java.net/~david/JDK-7169803/webrev.00/
>> <http://cr.openjdk.java.net/%7Edavid/JDK-7169803/webrev.00/>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-7169803
>>
>>
>> Testing: Passed JPRT
>>
>>
>> Thanks,
>> David
>>
>>
>>
>>
>>
>
>
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