RFR rev1 (M): 8078556: Runtime: implement ranges (optionally constraints) for those flags that have them missing

[Lindenmaier, Goetz]

Hi Gerard,

I would have appreciated to see another webrev, especially as you edited
the fixes I proposed.

The patch removing the flags from globals_linux_ppc.hpp was missing.
This breaks the build. Martin was so friendly to fix this.

You moved setting lower bound of StackShadowPages etc to '1'  to globals_ppc.hpp.
This helps with our tests running on our ppc machine with 64K pages. But Linux systems
on other cpus can also be configured to have >8K pages, and will run into
the error at os_linux.cpp:4648.  I guess you should open a follow-up bug for
this.  Or is there another workaround for this I oversee?

Nevertheless, still thanks for incorporating my changes.

Best regards,
  Goetz.



> -----Original Message-----
> From: gerard ziemski [mailto:gerard.ziemski at oracle.com]
> Sent: Mittwoch, 14. Oktober 2015 17:32
> To: Lindenmaier, Goetz; Dmitry Dmitriev; hotspot-runtime-
> dev at openjdk.java.net; Coleen Phillimore
> Subject: Re: RFR rev1 (M): 8078556: Runtime: implement ranges (optionally
> constraints) for those flags that have them missing
> 
> hi Goetz,
> 
> Great work, thank you for all the feedback, please see my answers inline:
> 
> 
> On 10/14/2015 04:00 AM, Lindenmaier, Goetz wrote:
> > Hi Gerald,
> >
> > I had a closer look at your change now, especially on the settings of the
> > stack protection zone sizes.
> >
> > You set the lower bounds of the stack protection pages > 1. Because of that
> > the VM on PPC does not start up, it immediately fails with:
> >    intx StackYellowPages=1 is outside the allowed range [ 6 ... 11 ]
> >    intx StackShadowPages=1 is outside the allowed range [ 8 ... 38 ]
> >    Error: Could not create the Java Virtual Machine.
> >    Error: A fatal exception has occurred. Program will exit.
> >
> > The lower bounds of these flags must be '1'.  If vm_page_size() >
> vm_default_page_size(),
> > the numbers of pages are reduced.  This is necessary
> > on systems with page size 64K, else stacks get too big.  We have such
> > systems on ppc.  See also os_linux.cpp:4649.
> >
> 
> PPC issue I will have to comment on later.
> 
> 
> >
> http://cr.openjdk.java.net/~gziemski/8078556_rev2/src/cpu/sparc/vm/glob
> als_sparc.hpp.udiff.html
> > Why do you need to special-case for !LP64 on sparc?  As I understand,
> > this is no more supported in jdk9.
> >
> 
> I'd prefer to keep the code in for completeness for those who will be reading
> that header.
> 
> 
> > in globals.hpp:
> >
> http://cr.openjdk.java.net/~gziemski/8078556_rev2/src/share/vm/runtime/
> globals.hpp.udiff.html
> >
> > You might want to use SIZE_MAX for MaxDirectMemorySize:
> >     product(size_t, MaxDirectMemorySize, 0,                                   \
> > +           range(0, (size_t)max_uintx)                                      \
> >
> 
> I like that. I will see if all the platforms are happy with SIZE_MAX
> 
> 
> > This lower bound setting crashes the VM on linuxx86_64 and seems
> pointless:
> >      product_pd(intx, ThreadStackSize,                                         \
> > +           range(0, max_intx-os::vm_page_size())                             \
> > bin/java -XX:ThreadStackSize=0
> > #  Internal Error (.../src/os/linux/vm/os_linux.cpp:720), pid=47259,
> tid=47260
> > #  assert(JavaThread::stack_size_at_create() > 0) failed: this should be set
> >
> 
> Yes, this is a follow-up issue tracked by
> https://bugs.openjdk.java.net/browse/JDK-8136766
> 
> 
> > More crashes I see on linuxx86_64:
> > bin/java -XX:MallocMaxTestWords=1
> > # There is insufficient memory for the Java Runtime Environment to
> continue.
> > # Native memory allocation (malloc) failed to allocate 18 bytes for
> AllocateHeap
> >
> 
> Right, this flag will be disabled from testing by the
> runtime/CommandLine/OptionsValidation as the valid values are in
> fact allowed to crash the VM for testing purposes, which is a behavior that
> can not be captured by the testing framework
> at the moment.
> 
> 
> > bin/java -XX:VMThreadStackSize=9007199254740991 / 4294967296 /
> 2147483648
> > # There is insufficient memory for the Java Runtime Environment to
> continue.
> > # Cannot create worker GC thread. Out of system resources.
> >
> 
> "Out of system resources" errors are in fact allowed. Still, is this a crash that
> dumps an error log? I do not see this
> issue in our internal testing, but I will verify on my local 64bit Linux (Ubuntu
> 14.04)
> 
> 
> > and on linuxppc64:
> > /sapmnt/home/d045726/oJ/vms/ppc_9-1/bin/java -
> XX:MaxRAM=18446744073709551615
> > OpenJDK 64-Bit Server VM warning: INFO:
> os::commit_memory(0x0000000082000000, 32178700288, 0) failed;
> error='Cannot allocate memory' (errno=12)
> > # There is insufficient memory for the Java Runtime Environment to
> continue.
> > # Native memory allocation (mmap) failed to map 32178700288 bytes for
> committing reserved memory.
> >
> 
> PPC issue I will have to comment on later.
> 
> 
> > I saw these errors trying to run
> > runtime/CommandLine/OptionsValidation/TestOptionsWithRanges.java
> > with a debug build.
> >
> > If you need any more input, especially on ppc, I'm happy to help out!
> 
> That would be great! I will reach out to you regarding PPC support after I look
> into it more.
> 
> Big thank you for the review!
> 
> 
> cheers