On Tue, 8 Nov 2016, Andrew Morton wrote:
> > Reading /proc/slabinfo or monitoring slabtop(1) can become very expensive
> > if there are many slab caches and if there are very lengthy per-node
> > partial and/or free lists.
> >
> > Commit 07a63c41fa1f ("mm/slab: improve performance of gathering slabinfo
> > stats") addressed the per-node full lists which showed a significant
> > improvement when no objects were freed. This patch has the same
> > motivation and optimizes the remainder of the usecases where there are
> > very lengthy partial and free lists.
> >
> > This patch maintains per-node active_slabs (full and partial) and
> > free_slabs rather than iterating the lists at runtime when reading
> > /proc/slabinfo.
>
> Are there any nice numbers you can share?
>
Yes, please add this to the description:
When allocating 100GB of slab from a test cache where every slab page is
on the partial list, reading /proc/slabinfo (includes all other slab
caches on the system) takes ~247ms on average with 48 samples.
As a result of this patch, the same read takes ~0.856ms on average.
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