Re: what is the purpose of SLAB and SLUB

From	Christoph Lameter <cl@linux.com>
Newsgroups	linux.kernel
Subject	Re: what is the purpose of SLAB and SLUB
Date	2016-08-29 16:50 +0200
Message-ID	<sbw2R-62-9@gated-at.bofh.it> (permalink)
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On Mon, 29 Aug 2016, Michal Hocko wrote:

> Compaction can certainly help and the more we are proactive in that
> direction the better. Vlastimil has already done a first step in that
> direction and we a have a dedicated kcompactd kernel thread for that
> purpose. But I guess what Mel had in mind is the latency of higher
> order pages which is inherently higher with the current page allocator
> no matter how well the compaction works. There are other changes, mostly
> for the fast path, needed to make higher order pages less of a second
> citizen.

Compaction needs to be able to move many more types of kernel objects out
of the way. I think if the callbacks that were merged for the migration of
CMA pages are made usable for slab allocations then we may make some
progress there. This would require the creator of a slab cache to specify
functions that allow the migration of an object. Would require additional
subsystem specific code. But doing that for inodes and dentries could be
very benficial for compaction.

Thread

Re: what is the purpose of SLAB and SLUB (was: Re: [PATCH v3]  mm/slab: Improve performance of gathering slabinfo) stats Mel Gorman <mgorman@suse.de> - 2016-08-25 12:10 +0200
  Re: what is the purpose of SLAB and SLUB (was: Re: [PATCH v3] mm/slab:  Improve performance of gathering slabinfo) stats Christoph Lameter <cl@linux.com> - 2016-08-25 22:00 +0200
    Re: what is the purpose of SLAB and SLUB Andi Kleen <andi@firstfloor.org> - 2016-08-26 22:50 +0200
      Re: what is the purpose of SLAB and SLUB Michal Hocko <mhocko@kernel.org> - 2016-08-29 15:50 +0200
        Re: what is the purpose of SLAB and SLUB Christoph Lameter <cl@linux.com> - 2016-08-29 16:50 +0200
    Re: what is the purpose of SLAB and SLUB (was: Re: [PATCH v3]  mm/slab: Improve performance of gathering slabinfo) stats Mel Gorman <mgorman@suse.de> - 2016-08-30 11:50 +0200
      Re: what is the purpose of SLAB and SLUB (was: Re: [PATCH v3] mm/slab:  Improve performance of gathering slabinfo) stats Christoph Lameter <cl@linux.com> - 2016-08-30 21:40 +0200

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