RFR(xs): 8079449: Improve os::attempt_reserve_memory_at() fallback coding on Linux, BSD, Solaris

[Thomas Stüfe]

Hi all,

please take a look at the following patch:

http://cr.openjdk.java.net/~stuefe/webrevs/8079449/webrev.00/webrev/
https://bugs.openjdk.java.net/browse/JDK-8079449

More details are in my original mail:
http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2015-April/014600.html


This patch adds a fix to fallback coding used in
os::attempt_reserve_memory_at() on Linux and BSD.

If this patch meets with approval, I will port the fix to Solaris, but
Solaris implementation was just different enough for this to be not
straightforward. Therefore I'd like to get some feedback for this issue
first.

Note - as I wrote in my original mail - that I have my doubts that this
fallback coding is even needed at all - in tests I never saw it doing
anything useful. I'd actually rather just remove it than fix it. What do
you think?`

Kind Regards, Thomas