RFR(xs): 8202772: NMT erroneously assumes thread stack boundaries to be page aligned

[Thomas Stüfe]

Thanks goetz!

On Tue, Jun 12, 2018, 09:03 Lindenmaier, Goetz <goetz.lindenmaier at sap.com>
wrote:

> Hi Thomas,
>
> looks good.
>
> Best regards,
>   Goetz.
>
> > -----Original Message-----
> > From: hotspot-runtime-dev [mailto:hotspot-runtime-dev-
> > bounces at openjdk.java.net] On Behalf Of Thomas Stüfe
> > Sent: Dienstag, 12. Juni 2018 06:59
> > To: Hotspot dev runtime <hotspot-runtime-dev at openjdk.java.net>
> > Subject: RFR(xs): 8202772: NMT erroneously assumes thread stack
> > boundaries to be page aligned
> >
> > Dear all,
> >
> > may I please have reviews for this fix, which - for now - disables
> > thread stack tracking for NMT on AIX.
> >
> > Bug: https://bugs.openjdk.java.net/browse/JDK-8202772
> > Webrev: http://cr.openjdk.java.net/~stuefe/webrevs/8202772-NMT-
> > erroneously-assumes-thread-stack-boundaries-to-be-page-
> > aligned/webrev.00/webrev/
> >
> > On AIX, we have two problems:
> >
> > - NMT assumes stack boundaries to be page aligned. This is wrong but
> > on all platforms other than AIX does not matter.
> > - the way mincore() is used to read residency of pages needs to be
> > adapted since on AIX, os::vm_page_size() is not necessarily the page
> > size used by mincore() - which is quite dangerous.
> >
> > Since JDK-8204552 was added to deal with the first point, it makes
> > sense to wait until that issue is finished. Until then, I'd like to
> > disable thread stack recognition in NMT for AIX. We can revisit this
> > topic again once we can spare time for it and JDK-8204552 has been
> > done.
>