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

[Erik Österlund]

Hi Stefan,

Thank you for the review.

/Erik

> On 30 Oct 2019, at 11:50, Stefan Karlsson <stefan.karlsson at oracle.com> wrote:
> 
> 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
>>>>