Am 05.09.19 um 14:15 schrieb Vlastimil Babka:
> 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"")
No it's a vm running inside qemu/kvm without numa.
Greets,
Stefan
