On 9/5/19 1:27 PM, Stefan Priebe - Profihost AG wrote:
> Hello all,
>
> i hope you can help me again to understand the current MemAvailable
> value in the linux kernel. I'm running a 4.19.52 kernel + psi patches in
> this case.
>
> I'm seeing the following behaviour i don't understand and ask for help.
>
> While MemAvailable shows 5G the kernel starts to drop cache from 4G down
> to 1G while the apache spawns some PHP processes. After that the PSI
> mem.some value rises and the kernel tries to reclaim memory but
> MemAvailable stays at 5G.
>
> Any ideas?
PHP seems to use madvise(MADV_HUGEPAGE), so if it's a NUMA machine it
might be worth trying to cherry-pick these two commits:
92717d429b38 ("Revert "Revert "mm, thp: consolidate THP gfp handling
into alloc_hugepage_direct_gfpmask""")
a8282608c88e ("Revert "mm, thp: restore node-local hugepage allocations"")
> Thanks!
>
> Greets,
> Stefan
>
>
