Huge pages on PPC64

[Volker Simonis]

Just a quick question: do you also get the same warnings if you are
running without compressed oops (i.e. -XX:-UseCompressedClassPointers
-XX:-UseCompressedOops)? If not maybe this is related to the fact that
for compressed oops we try to allocate memory in low memory regions.

On Mon, Oct 24, 2016 at 6:50 PM, Gustavo Romero
<gromero at linux.vnet.ibm.com> wrote:
> Hi,
>
> Is Huge Pages properly supported by OpenJDK on PPC64 and PPC64 LE?
>
> I did a simple test like:
>
> # uname -a
> Linux tm 4.4.0-38-generic #57-Ubuntu SMP Tue Sep 6 15:42:33 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
> # fgrep Huge /proc/meminfo
> AnonHugePages:     12288 kB
> HugePages_Total:     256
> HugePages_Free:      256
> HugePages_Rsvd:        0
> HugePages_Surp:        0
> Hugepagesize:       2048 kB
> # java -XX:+PrintCommandLineFlags -XX:+UseLargePages -Xms256m -Xmx256m StrictMath_cos
> -XX:InitialHeapSize=268435456 -XX:MaxHeapSize=268435456 -XX:+PrintCommandLineFlags -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseLargePages -XX:+UseParallelGC
> 0.1709843554185943
> # java -version
> openjdk version "1.8.0_91"
> OpenJDK Runtime Environment (build 1.8.0_91-8u91-b14-3ubuntu1~16.04.1-b14)
> OpenJDK 64-Bit Server VM (build 25.91-b14, mixed mode)
>
>
> on x64 all went well, but on PPC64 I'm getting an error as if the amount
> of space requested was greater than HugePages_Total * Hugepagesize, which
> is no true:
>
> # uname -a
> Linux pub 4.5.0-rc4-powerpc64le #1 SMP Debian 4.5~rc4-1~exp1 (2016-02-18) ppc64le GNU/Linux
> # fgrep Huge /proc/meminfo
> AnonHugePages:   7831552 kB
> HugePages_Total:    1024
> HugePages_Free:     1024
> HugePages_Rsvd:        0
> HugePages_Surp:        0
> Hugepagesize:      16384 kB
> # java -XX:+PrintCommandLineFlags -Xms256m -Xmx256m -XX:+UseLargePages StrictMath_cos
> -XX:InitialHeapSize=268435456 -XX:MaxHeapSize=268435456 -XX:+PrintCommandLineFlags -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseLargePages -XX:+UseParallelGC
> OpenJDK 64-Bit Server VM warning: Failed to reserve large pages memory req_addr: 0x00000000f0000000 bytes: 268435456 (errno = 16).
> OpenJDK 64-Bit Server VM warning: Failed to reserve large pages memory req_addr: 0x00000007b0000000 bytes: 268435456 (errno = 16).
> OpenJDK 64-Bit Server VM warning: Failed to reserve large pages memory req_addr: 0x0000000000000000 bytes: 301989888 (errno = 16).
> # java -version
> openjdk version "1.8.0_102"
> OpenJDK Runtime Environment (build 1.8.0_102-8u102-b14.1-2-b14)
> OpenJDK 64-Bit Server VM (build 25.102-b14, mixed mode)
>
>
> Am I missing something here or something is planned (tho I could not find a JEP or JBS on it...)?
>
> Thank you.
>
>
> Regards,
> Gustavo
>