Check the default huge page size for Linux

[hankluo6]

In Linux, we can read /proc/meminfo to get the huge page size.

Please node that this will get only one possible size, but Linux can supports more than one huge page size.

[daanx]

Thanks for the PR! and apologies for being so late addressing this :-(.
But yikes -- this is so fragile; very hesitant to include this ... it may be the only way to get the large page size though so perhaps it is what it is :-). I need to think a bit more on this.

[scottlamb]

I believe there's another interface that requires less parsing, described here:

Some userspace (such as a test program, or an optimized memory allocation library) may want to know the size (in bytes) of a PMD-mappable transparent hugepage:

cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size

On my system:

$ uname -a
Linux slamb-workstation 6.11.0-19-generic #19~24.04.1-Ubuntu SMP PREEMPT_DYNAMIC Mon Feb 17 11:51:52 UTC 2 x86_64 x86_64 x86_64 GNU/Linux
$ cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
2097152