On 9/9/19 2:09 PM, Stefan Priebe - Profihost AG wrote:
Am 09.09.19 um 13:49 schrieb Vlastimil Babka:
On 9/9/19 10:54 AM, Stefan Priebe - Profihost AG wrote:
Do you have more snapshots of /proc/vmstat as suggested by Vlastimil and
me earlier in this thread? Seeing the overall progress would tell us
much more than before and after. Or have I missed this data?
I needed to wait until today to grab again such a situation but from
what i know it is very clear that MemFree is low and than the kernel
starts to drop the chaches.
Attached you'll find two log files.
Thanks, what about my other requests/suggestions from earlier?
Sorry i missed your email.
1. How does /proc/pagetypeinfo look like?
# cat /proc/pagetypeinfo
Page block order: 9
Pages per block: 512
Looks like it might be fragmented, but was that snapshot taken in the
situation where there's free memory and the system still drops cache?
2. Could you also try if the bad trend stops after you execute:
echo never > /sys/kernel/mm/transparent_hugepage/defrag
and report the result?
it's pretty difficult to catch those moments. Is it OK so set the value
now and monitor if it happens again?
Well if it doesn't happen again after changing that setting, it would
definitely point at THP interactions.
Just to let you know:
I've now also some more servers where memfree show 10-20Gb but cache
drops suddently and memory PSI raises.
You mean those are in that state right now? So how does
/proc/pagetypeinfo look there, and would changing the defrag setting help?
Greets,
Stefan
