Re: [PATCH 3/3] mm: oom: show unreclaimable slab info when unreclaimable slabs > user memory

[Yang Shi]

On 10/19/17 12:28 AM, Michal Hocko wrote:
> On Tue 17-10-17 15:39:08, David Rientjes wrote:
> > On Wed, 18 Oct 2017, Yang Shi wrote:
> >
> > > > Yes, this should catch occurrences of "huge unreclaimable slabs", right?
> > >
> > > Yes, it sounds so. Although single "huge" unreclaimable slab might not result
> > > in excessive slabs use in a whole, but this would help to filter out "small"
> > > unreclaimable slab.
> >
> > Keep in mind this is regardless of SLAB_RECLAIM_ACCOUNT: your patch has
> > value beyond only unreclaimable slab, it can also be used to show
> > instances where the oom killer was invoked without properly reclaiming
> > slab.  If the total footprint of a slab cache exceeds 5%, I think a line
> > should be emitted unconditionally to the kernel log.
>
> agreed. I am not sure 5% is the greatest fit but we can tune that later.

5% might be too few. For example, on a machine with 200G memory, if 
there is 80G page cache, radix_tree_node might consume 10G. IMHO, 10% 
might be better.

Yang

>