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

Lindenmaier, Goetz goetz.lindenmaier at sap.com
Fri Oct 16 13:11:19 UTC 2015

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 vmpagesize() > vmdefaultpagesize(), > 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 oslinux.cpp:4649. > PPC issue I will have to comment on later. > http://cr.openjdk.java.net/~gziemski/8078556rev2/src/cpu/sparc/vm/glob alssparc.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/8078556rev2/src/share/vm/runtime/ globals.hpp.udiff.html > > You might want to use SIZEMAX for MaxDirectMemorySize: _> product(sizet, MaxDirectMemorySize, 0, _ _> + range(0, (sizet)maxuintx) _ > I like that. I will see if all the platforms are happy with SIZEMAX > This lower bound setting crashes the VM on linuxx8664 and seems pointless: _> productpd(intx, ThreadStackSize, _ _> + range(0, maxintx-os::vmpagesize()) _ > bin/java -XX:ThreadStackSize=0 > # Internal Error (.../src/os/linux/vm/oslinux.cpp:720), pid=47259, tid=47260 > # assert(JavaThread::stacksizeatcreate() > 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 linuxx8664: > 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/ppc9-1/bin/java - XX:MaxRAM=18446744073709551615 > OpenJDK 64-Bit Server VM warning: INFO: os::commitmemory(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

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