[jdk21u-dev] RFR: 8320061: [nmt] Multiple issues with peak accounting

[María Arias de Reyna]

On Wed, 10 Apr 2024 08:35:59 GMT, María Arias de Reyna <duke at openjdk.org> wrote:

> This is a follow up of https://github.com/openjdk/jdk21u-dev/pull/440
> 
> This backport fixes several NMT things, among those, the problem with largest_committed being 0KB as shown on the previous PR.
> 
> Example of output:
> 
> 
> $ jcmd 20088 VM.native_memory detail | grep "mmap: reserved="
>                             (mmap: reserved=8388608KB, committed=618496KB, at peak) 
>                             (mmap: reserved=1048576KB, committed=32064KB, at peak) 
>                             (mmap: reserved=528392KB, committed=41416KB, at peak) 
>                             (mmap: reserved=197140KB, committed=45380KB, at peak) 
>                             (mmap: reserved=40KB, committed=36KB, at peak) 
>                             (mmap: reserved=8KB, committed=8KB, at peak) 
>                             (mmap: reserved=262144KB, committed=224640KB, at peak) 
>                             (mmap: reserved=0KB, committed=0KB, peak=20KB) 
> 
> As described in the original PR, other features in this PR is fixing the scale so it also shows when the allocation value is zero (note the GB now instead of showing KB as before, and the *0GB* that is shown):
> 
> 
> $ jcmd 20088 VM.native_memory detail scale=g | grep "committed"
> Total: reserved=11GB, committed=2GB
>        mmap:   reserved=10GB, committed=1GB
> -                 Java Heap (reserved=8GB, committed=1GB)
>                             (mmap: reserved=8GB, committed=1GB, at peak) 
> -                     Class (reserved=1GB, committed=0GB)
>                             (mmap: reserved=1GB, committed=0GB, at peak) 
>                             (    reserved=0GB, committed=0GB)
>                             (    reserved=1GB, committed=0GB)
> -                      Code (reserved=1GB, committed=0GB)
>                             (mmap: reserved=1GB, committed=0GB, at peak) 
> -                     Other (reserved=1GB, committed=1GB)
> 	[0x00000005c0000000 - 0x0000000601c00000] committed 1GB from
>                              (reserved=8GB, committed=1GB Type=Java Heap)
>                              (reserved=1GB, committed=0GB Type=Class)
>                              (reserved=1GB, committed=0GB Type=Code)

This is a clean merge to another open PR.

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PR Comment: https://git.openjdk.org/jdk21u-dev/pull/481#issuecomment-2046938838