RFR: 8224817: Implementation of JEP 364: ZGC on macOS

[Stefan Karlsson]

Hi Erik,

Reviewed:
https://cr.openjdk.java.net/~eosterlund/8224817/webrev.02

Looks good.

Thanks,
StefanK


On 2019-10-29 12:31, erik.osterlund at oracle.com wrote:
> Seems reasonable. Thanks.
> 
> /Erik
> 
> On 10/29/19 12:29 PM, Per Liden wrote:
>> Some suggested adjustments, already discussed with Erik off-line:
>>
>> http://cr.openjdk.java.net/~pliden/8224817/webrev.review.0
>>
>> /Per
>>
>> On 10/28/19 5:11 PM, Erik Österlund wrote:
>>> Hi,
>>>
>>> After some internal discussions with Per and Stefan, some 
>>> refactorings have been made:
>>>
>>> 1) Use mmap consistently wherever possibly, instead of mach_vm_map, 
>>> for consistency. And only use mach_vm_remap from a wrapper function 
>>> to map in views.
>>> 2) Move the pmem segments up one level so that producer and consumer 
>>> of the segments is on the same level, and let the virtual "file" know 
>>> only about offsets.
>>> 3) Minor polishing.
>>>
>>> Incremental:
>>> http://cr.openjdk.java.net/~eosterlund/8224817/webrev.00..01/
>>>
>>> Full:
>>> http://cr.openjdk.java.net/~eosterlund/8224817/webrev.01/
>>>
>>> Thanks,
>>> /Erik
>>>
>>> On 2019-10-24 12:38, erik.osterlund at oracle.com wrote:
>>>> Hi,
>>>>
>>>> Now that some curling has been performed, paving way for this patch:
>>>>
>>>>     8229027: Improve how JNIHandleBlock::oops_do distinguishes oops 
>>>> from non-oops
>>>>     8229278: Improve hs_err location printing to assume less about 
>>>> GC internals
>>>>     8229189: Improve JFR leak profiler tracing to deal with 
>>>> discontiguous heaps
>>>>     8224815: Remove non-GC uses of CollectedHeap::is_in_reserved()
>>>>     8224820: ZGC: Support discontiguous heap reservations
>>>>
>>>> ...the remaining thing to do is plugging in a few platform specific 
>>>> ZGC files. This patch does that.
>>>> Decided to go with mach_vm_map/mach_vm_remap to implement 
>>>> multi-mapping. Previously I didn't want to do that as I couldn't 
>>>> figure out how to mach_vm_remap memory on top of reserved VA 
>>>> (acquired using mmap). But apparently VM_FLAGS_OVERWRITE was the 
>>>> missing ingredient there. With that in place, dodging the terrible 
>>>> ftruncate implementation on macOS seemed like a good idea. That also 
>>>> implies this port supports large pages (unlike other GCs on macOS 
>>>> today). Yay!
>>>>
>>>> CR:
>>>> http://cr.openjdk.java.net/~eosterlund/8224817/webrev.00/
>>>>
>>>> Bug:
>>>> https://bugs.openjdk.java.net/browse/JDK-8229358
>>>>
>>>> Thanks,
>>>> /Erik
>>>
>