RFR(S) 8233093: Move CDS heap oopmaps into new MetaspaceShared::bm region

[Calvin Cheung]

Thanks Yumin and Ioi.
I've pushed the changeset.

Calvin

On 3/26/20 9:49 AM, Yumin Qi wrote:
> Hi, Calvin
>
> Looks good to me.
>
> Thanks
> Yumin
>
>
>
> On 3/25/20 1:56 PM, Calvin Cheung wrote:
>> Hi Ioi,
>>
>> Thanks for your review.
>>
>> On 3/25/20 11:26 AM, Ioi Lam wrote:
>>> Hi Calvin,
>>>
>>> Looks good. Just some minor nits for filemap.cpp:
>>>
>>> 1244   if (closed_oopmaps != NULL && open_oopmaps != NULL) {
>>> 1245     size_t curr_offset = write_oopmaps(closed_oopmaps, 
>>> ptrmap->size_in_bytes(), buffer);
>>> 1246     curr_offset = write_oopmaps(open_oopmaps, curr_offset, 
>>> buffer);
>>>
>>> There's no need to write to curr_offset on line 1246.
>>>
>> Fixed.
>>> ----
>>>
>>> Unnecessary new line at 1897.
>>>
>> Removed.
>>> ----
>>>
>>> 1599     current_info()->unmap_region(MetaspaceShared::bm);
>>>
>>> This call can be removed, because the "bm" region will be eventually 
>>> unmapped by the new code in 
>>> MetaspaceShared::initialize_shared_spaces(). This way, if we later 
>>> need to relocate the archived heap relocation, there's no need to 
>>> map the "bm" region again.
>>
>> I've replaced it with a comment.
>>
>> updated webrev:
>>
>>     http://cr.openjdk.java.net/~ccheung/jdk15/8233093/webrev.01/
>>
>> thanks,
>>
>> Calvin
>>
>>>
>>> Thanks
>>> - Ioi
>>>
>>>
>>> On 3/25/20 9:39 AM, Calvin Cheung wrote:
>>>> RFE: https://bugs.openjdk.java.net/browse/JDK-8233093
>>>>
>>>> webrev: http://cr.openjdk.java.net/~ccheung/jdk15/8233093/webrev.00/
>>>>
>>>> The MetaspaceShared::bm region was introduced via JDK-8231610 
>>>> (Relocate the CDS archive if it cannot be mapped to the requested 
>>>> address) and only used during archive loading. The region will be 
>>>> unmapped afterwards to save memory footprint. Since the heap 
>>>> oopmaps are also only used during archive loading, it makes sense 
>>>> for them to reside in the "bm" region as well.
>>>>
>>>> Before:
>>>> [0.753s][debug][cds] ro space: 7552120 [ 59.7% of total] out of 
>>>> 7553024 bytes [100.0% used] at 0x00000008003e1000
>>>> [0.753s][debug][cds] bm space: 184320 [ 1.5% of total] out of 
>>>> 184320 bytes [100.0% used] at 0x0000000000000000
>>>>
>>>> After:
>>>> [0.766s][debug][cds] ro space: 7525856 [ 59.5% of total] out of 
>>>> 7528448 bytes [100.0% used] at 0x00000008003e1000
>>>> [0.766s][debug][cds] bm space: 208896 [ 1.7% of total] out of 
>>>> 208896 bytes [100.0% used] at 0x0000000000000000
>>>>
>>>> Passed tiers 1 - 4 testing.
>>>>
>>>> thanks,
>>>>
>>>> Calvin
>>>>
>>>
>