RFR: 8212995: Consider placing the Integer.IntegerCache and cached Integer objects in the closed archive heap region
Jiangli Zhou
jiangli.zhou at oracle.com
Wed Oct 31 19:08:11 UTC 2018
Hi Ioi,
Here is an updated webrev with renaming of the 'is_shared' argument. I
decided to go with your suggestion, 'is_closed_archive'.
http://cr.openjdk.java.net/~jiangli/8212995/webrev.01/
Thanks,
Jiangli
On 10/30/18 4:19 PM, Jiangli Zhou wrote:
> Hi Ioi,
>
> On 10/30/18 3:00 PM, Ioi Lam wrote:
>
>> Hi Jiangli,
>>
>> This looks promising.
>>
>> Now a full review yet, but I am wondering about the name of the
>> is_shared parameter
>>
>> void add_subgraph_entry_field(int static_field_offset, oop v, bool
>> is_shared);
>>
>> Since this is part of "heapShared", everything is "shared" in some
>> sense of the word. It could be confusing to say something is more
>> shared than other things which also shared ...
>>
>> How "is_closed_archive" instead?
> Yes, our 'shared' has broader meaning. "is_closed_archive" or
> "is_closed_space" sounds good to me. I'll rename.
>
> Thanks,
> Jiangli
>>
>> Thanks
>> - Ioi
>>
>>
>> On 10/30/2018 01:57 PM, Jiangli Zhou wrote:
>>> Please review the following change for moving the archived
>>> Integer.IntegerCache and it's cached Integer objects (256) to the
>>> closed archiving heap region. The IntegerCache subgraph does not
>>> contain any reference that's changed at runtime (good candidate for
>>> sharing). Moving the whole subgraph into the closed archive heap
>>> region allows the memory to be shared by different JVM instances at
>>> runtime. The saving is 4K per JVM instance running the same or
>>> different java application simultaneously. Although 4K is not
>>> significant, in a larger picture the saving is much bigger (4k *
>>> (JVM_instance_num - 1) * host_num).
>>>
>>> As part of the change, I also restructured the code to allow us to
>>> plug in more shareable subgraphs in the closed archive heap region
>>> for runtime footprint saving in the future.
>>>
>>> The 'st' space is renamed to 'ca' (closed archive) space since it
>>> now contains other types of objects besides j.l.Strings.
>>>
>>> webrev: http://cr.openjdk.java.net/~jiangli/8212995/webrev.00/
>>> RFE: https://bugs.openjdk.java.net/browse/JDK-8212995
>>>
>>> Before:
>>>
>>> mc space: 8416 [ 0.0% of total] out of 12288 bytes [
>>> 68.5% used] at 0x0000000800000000
>>> rw space: 3946640 [ 21.4% of total] out of 3948544 bytes
>>> [100.0% used] at 0x0000000800003000
>>> ro space: 7319328 [ 39.6% of total] out of 7319552 bytes
>>> [100.0% used] at 0x00000008003c7000
>>> md space: 2416 [ 0.0% of total] out of 4096 bytes [
>>> 59.0% used] at 0x0000000800ac2000
>>> od space: 6475944 [ 35.0% of total] out of 6479872 bytes [
>>> 99.9% used] at 0x0000000800ac3000
>>> st0 space: 438272 [ 2.4% of total] out of 438272 bytes
>>> [100.0% used] at 0x00000007ffc00000 <<<<<<<<<<
>>> oa0 space: 282624 [ 1.5% of total] out of 282624 bytes
>>> [100.0% used] at 0x00000007ff800000 <<<<<<<<<<
>>> total : 18473640 [100.0% of total] out of 18485248 bytes [
>>> 99.9% used]
>>>
>>> After:
>>>
>>> mc space: 8416 [ 0.0% of total] out of 12288 bytes [
>>> 68.5% used] at 0x0000000800000000
>>> rw space: 3946640 [ 21.4% of total] out of 3948544 bytes
>>> [100.0% used] at 0x0000000800003000
>>> ro space: 7319304 [ 39.6% of total] out of 7319552 bytes
>>> [100.0% used] at 0x00000008003c7000
>>> md space: 2416 [ 0.0% of total] out of 4096 bytes [
>>> 59.0% used] at 0x0000000800ac2000
>>> od space: 6475920 [ 35.0% of total] out of 6479872 bytes [
>>> 99.9% used] at 0x0000000800ac3000
>>> ca0 space: 442368 [ 2.4% of total] out of 442368 bytes
>>> [100.0% used] at 0x00000007ffc00000 <<<<<<<<<<
>>> oa0 space: 278528 [ 1.5% of total] out of 278528 bytes
>>> [100.0% used] at 0x00000007ff800000 <<<<<<<<<<
>>> total : 18473592 [100.0% of total] out of 18485248 bytes [
>>> 99.9% used]
>>>
>>> Tested with appcds tests on linux-x64 locally. Running tier1-teir4
>>> tests.
>>>
>>> Thanks,
>>>
>>> Jiangli
>>>
>>>
>>
>
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