[aarch64-port-dev ] RFR: initial patches for merge up to jdk8-b117

[Andrew McDermott]

>> However, I did ran into problems with some of the jtreg tests using all
>> the available memory on my machine (32GB). That, combined with only a
>> 100MB swap file, caused my machine to hang hard quite a few times over
>> the last two days and the reboots required most of my file systems to be
>> fsck'd, which took quite some time as there is ~4TB spread across 5
>> disks.  I'll run the tests again and report back which tests I believe
>> are using/requesting a lot of memory but right now I wanted to get these
>> patches out for review.
>
> I wanted to follow up on this problem.
>
> This spike (which you can see in the attached image) comes from running
> the following test:

I think the list swallowed the attachment.  There's a copy here:

  http://people.linaro.org/~andrew.mcdermott/RunUnitTestsConcurrently.png

>
>  $ jtreg -conc:1 -v1 -a \
>    -retain:none \
>    -jdk:/jdk8-b117/build/linux-x86_64-normal-server-fastdebug/images/j2sdk-image \
>    runtime/memory/RunUnitTestsConcurrently.java
>
> However, if I run using 'release' then the same memory pattern is not
> exhibited, and in fact the test runs very quickly - which you would
> expect as it's not trying to gobble 30+GB of ram.
>
> So the reason why my machine was sometimes [1] hanging hard was due to
> the deliberately small swap partition I use and because I was running
> many other tests and builds at the same time, and typically with a
> concurrency factor of 10.
>
> It's odd (and I have done zero investigation other than identify which
> particular test it is) as to why the same test under different build
> configurations behaves the way it does.
>
> [1] Sometimes the OOM killer protected me.
>
> Dec 13 08:34:43 spicy kernel: [39733.368142] Out of memory: Kill process 1884 (java) score 854 or sacrifice child
> Dec 13 08:34:43 spicy kernel: [39733.368148] Killed process 1884 (java) total-vm:41047740kB, anon-rss:28193560kB, file-rss:16kB