Re: [PATCH] mm, memcg: reclaim more aggressively before high allocator throttling

[Chris Down]

Johannes Weiner writes:
> > I don't feel strongly either way, but current->memcg_nr_pages_over_high can
> > be very large for large allocations.
> >
> > That said, maybe we should just reclaim `max(SWAP_CLUSTER_MAX, current -
> > high)` for each loop? I agree that with this design it looks like perhaps we
> > don't need it any more.
> >
> > Johannes, what do you think?
>
> How about this:
>
> Reclaim memcg_nr_pages_over_high in the first iteration, then switch
> to SWAP_CLUSTER_MAX in the retries.
>
> This acknowledges that while the page allocator and memory.max reclaim
> every time an allocation is made, memory.high is currently batched and
> can have larger targets. We want the allocating thread to reclaim at
> least the batch size, but beyond that only what's necessary to prevent
> premature OOM or failing containment.
>
> Add a comment stating as much.
>
> Once we reclaim memory.high synchronously instead of batched, this
> exceptional handling is no longer needed and can be deleted again.
>
> Does that sound reasonable?

That sounds good to me, thanks. I'll change that in v2 soonish and update the 
changelog.