Re: Caching/buffers become useless after some time

[Marinko Catovic <marinko.catovic@gmail.com>]

Am Fr., 2. Nov. 2018 um 14:13 Uhr schrieb Vlastimil Babka <vbabka@suse.cz>:
>
> On 11/2/18 1:41 PM, Marinko Catovic wrote:
> >>>> any idea how to find out what that might be? I'd really have no idea,
> >>>> I also wonder why this never was an issue with 3.x
> >>>> find uses regex patterns, that's the only thing that may be unusual.
> >>>
> >>> The allocation tracepoint has the stack trace so that might help. This
> >>
> >> Well we already checked the mm_page_alloc traces and it seemed that only
> >> THP allocations could be the culprit. But apparently defrag=defer made
> >> no difference. I would still recommend it so we can see the effects on
> >> the traces. And adding tracepoints
> >> compaction/mm_compaction_try_to_compact_pages and
> >> compaction/mm_compaction_suitable as I suggested should show which
> >> high-order allocations actually invoke the compaction.
> >
> > Anything in particular I should do to figure this out?
>
> Setup the same monitoring as before, but with two additional tracepoints
> (echo 1 > .../enable) and once the problem appears, provide the tracing
> output.

I think I'll need more details about that setup  :)
also, do you want the tracing output every 5sec or just once when it
is around the worst case? what files exactly?