Re: [PATCH 3/3] mm: slub: Default slub_max_order to 0

Andrea Arcangeli
2011-05-12T18:10:06Z

On Thu, May 12, 2011 at 01:03:05PM -0500, Christoph Lameter wrote:
> On Thu, 12 May 2011, Andrea Arcangeli wrote:
>
> > even order 3 is causing troubles (which doesn't immediately make lumpy
> > activated, it only activates when priority is < DEF_PRIORITY-2, so
> > after 2 loops failing to reclaim nr_to_reclaim pages), imagine what
>
> That is a significant change for SLUB with the merge of the compaction
> code.

Even before compaction was posted, I had to shut off lumpy reclaim or
it'd hang all the time with frequent order 9 allocations. Maybe lumpy
was better before, maybe lumpy "improved" its reliability recently,
but definitely it wasn't performing well. That definitely applies to
>=2.6.32 (I had to nuke lumpy from it, and only keep compaction
enabled, pretty much like upstream with COMPACTION=y). I think I never
tried earlier lumpy code than 2.6.32, maybe it was less aggressive
back then, I don't exclude it but I thought the whole notion of lumpy
was to takedown everything in the way, which usually leads to process
hanging in swapins or pageins for frequent used memory.