RFR(XS): 8065050: vm crashes during CDS dump when very small SharedMiscDataSize is specified

David Holmes david.holmes at oracle.com
Fri Dec 5 04:08:37 UTC 2014


On 5/12/2014 12:40 PM, Calvin Cheung wrote:
> Hi David,
>
> On 12/4/2014 3:14 PM, David Holmes wrote:
>> On 4/12/2014 11:40 AM, Calvin Cheung wrote:
>>> Hi Jiangli,
>>>
>>> I've updated the webrev at the same location:
>>>      http://cr.openjdk.java.net/~ccheung/8065050/webrev/
>>
>> Seems okay. Do we have a test that sets the flags to these allowed
>> minimum values and dumps and then uses the archive?
>
> I've added more test scenarios to the testcase.
> Updated webrev is at the same location.

These values:

!                     value = Platform.is64bit() ? "10M" : "8M";
!                     break;
!                 case RW:
!                     value = Platform.is64bit() ? "13M" : "7M";

should match these:

      min_ro_size = NOT_LP64(7*M) LP64_ONLY(9*M),
      min_rw_size = NOT_LP64(6*M) LP64_ONLY(12*M)

David
-----

> thanks,
> Calvin
>
>
>>
>> Thanks,
>> David
>>
>>> Previous version is saved at:
>>>      http://cr.openjdk.java.net/~ccheung/8065050/webrev.00/
>>>
>>> thanks,
>>> Calvin
>>>
>>> On 12/3/2014 3:53 PM, Jiangli Zhou wrote:
>>>> Hi Calvin,
>>>>
>>>> On 12/03/2014 03:51 PM, Calvin Cheung wrote:
>>>>> On 12/3/2014 2:55 PM, Jiangli Zhou wrote:
>>>>>> Hi Calvin,
>>>>>>
>>>>>> It's better to define 12M and 16M as enums in metaspaceShared.hpp
>>>>>> now they are referenced in more than one place.
>>>>> So global.hpp will need to include metaspaceShared.hpp.
>>>>>>
>>>>>> I also have some questions. The 12M/16M are not introduced by this
>>>>>> change, do you know why those values were chosen as the default RO
>>>>>> and RW sizes?
>>>>> Sorry. I don't know the reasons why those values were chosen.
>>>>>> Now we require both spaces have to be at lease 12M on 32-bit
>>>>>> machines and 16M on 64-bit machine, is it a reasonable requirement?
>>>>>> What's the minimum size requirement for the RO and RW spaces with
>>>>>> the default classlist?
>>>>>
>>>>> Below are the numbers for the RO and RW spaces with the default
>>>>> classlist for various platforms:
>>>>> =====
>>>>> linux
>>>>> =====
>>>>> 64-bit
>>>>> ro space:   8433480 [ 37.8% of total] out of  16777216 bytes [50.3%
>>>>> used] at 0x0000000800000000
>>>>> rw space:  11418608 [ 51.1% of total] out of  16777216 bytes [68.1%
>>>>> used] at 0x0000000801000000
>>>>>
>>>>> 32-bit
>>>>> ro space:   6316488 [ 48.9% of total] out of  12582912 bytes [50.2%
>>>>> used] at 0x80000000
>>>>> rw space:   5794312 [ 44.9% of total] out of  12582912 bytes [46.0%
>>>>> used] at 0x80c00000
>>>>>
>>>>> ========
>>>>> windows
>>>>> ========
>>>>> 64-bit
>>>>> ro space:   7888680 [ 37.7% of total] out of  16777216 bytes [47.0%
>>>>> used] at 0x0000000800000000
>>>>> rw space:  10704496 [ 51.1% of total] out of  16777216 bytes [63.8%
>>>>> used] at 0x0000000801000000
>>>>>
>>>>> 32-bit
>>>>> ro space:   6030640 [ 49.3% of total] out of  12582912 bytes [47.9%
>>>>> used] at 0x14690000
>>>>> rw space:   5440904 [ 44.5% of total] out of  12582912 bytes [43.2%
>>>>> used] at 0x15290000
>>>>>
>>>>> ====
>>>>> mac
>>>>> ====
>>>>> 64-bit
>>>>> ro space:   6798968 [ 37.0% of total] out of  16777216 bytes [40.5%
>>>>> used] at 0x0000000800000000
>>>>> rw space:   9446240 [ 51.4% of total] out of  16777216 bytes [56.3%
>>>>> used] at 0x0000000801000000
>>>>>
>>>>> ====
>>>>>
>>>>> So maybe we can define some enums as follows and leave the default
>>>>> values in globals.hpp alone?
>>>>>
>>>>> min_ro_size  NOT_LP64(7*M) LP64_ONLY(9*M)
>>>>> min_rw_size  NOT_LP64(6*M) LP64_ONLY(12*M)
>>>>
>>>> Sounds good to me.
>>>>
>>>> Thanks,
>>>> Jiangli
>>>>
>>>>>
>>>>> thanks,
>>>>> Calvin
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Jiangli
>>>>>>
>>>>>> On 12/01/2014 12:10 PM, Calvin Cheung wrote:
>>>>>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8065050
>>>>>>>
>>>>>>> Adding more checks on the SharedMiscDataSize, ShareReadOnlySize,
>>>>>>> and SharedReadWriteSize.
>>>>>>>
>>>>>>> For the SharedMiscDataSize, it is based on
>>>>>>> MetaspaceShared::generate_vtable_methods(). Similar to what was
>>>>>>> done for the SharedMiscCodeSize.
>>>>>>>
>>>>>>> For the ShareReadOnlySize and SharedReadWriteSize, I'm checking if
>>>>>>> they are at least the default size.
>>>>>>> I think it's reasonable to enforce the ro and rw sizes to be at
>>>>>>> least the default size. A default dump of CDS archive requires >8M
>>>>>>> of ro space and >11M of rw space.
>>>>>>>
>>>>>>> webrev:
>>>>>>>     http://cr.openjdk.java.net/~ccheung/8065050/webrev/
>>>>>>>
>>>>>>> tests:
>>>>>>>     ran the testcase via jtreg on linux_x64 and windows_x64
>>>>>>>     JPRT
>>>>>>>
>>>>>>> thanks,
>>>>>>> Calvin
>>>>>>
>>>>>
>>>>
>>>
>


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