RFR 8204552: NMT: Separate thread stack tracking from virtual memory tracking

[yumin qi]

Hi,  Zhengyu

  Good to see tracking thread stack separated from tracking virtual memory.
It looks good to me.

Thanks
Yumin

On Mon, Feb 18, 2019 at 5:50 AM <zgu at redhat.com> wrote:

> NMT tracks thread stacks as virtual memory since day one, as most of
> platofrms are using virtual memory to back thread stacks. However,
> there are exceptions, e.g. AIX. The matter of fact, POSIX standard does
> not dictate what kind of memory or even alignment requirement for
> thread stacks.
>
> This patch separates thread stack tracking from virtual memory
> tracking. It delegates to virtual memory tracker if thread stack is
> backed by virtual memory.
>
> For thread stacks that are backed by malloc'd memory, it can not simply
> utilize malloc tracker for detail tracking, since it can not install
> tracking header in place. Therefore, it has to track those memory
> separately, then piggybacks to existing malloc tracking infrastructure
> during snapshot, for baselining and reporting.
>
> Thanks for Goetz Lindenmaier and Thomas Stüfe's help to run the patch
> through SAP buidling and testing infrastructure, that is especially
> helpful for verifying the fix for AIX.
>
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8204552
> Webrev: http://cr.openjdk.java.net/~zgu/JDK-8204552/webrev.01/
>
> Test:
>   hotspot_nmt on Linux x64 (fastdebug and release)
>
> Thanks,
>
> -Zhengyu
>
>
>
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