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

[Calvin Cheung]

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)

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
>