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

[Jiangli Zhou]

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
>>
>