Re: [PATCH][RFC] slub: increasing order reduces memory usage of somekey caches

[Christoph Lameter]

Richard Kennedy wrote:

> Slabcache: dentry                Aliases:  0 Order :  0 Objects: 22553
> ** Reclaim accounting active
> 
> Sizes (bytes)     Slabs              Debug                Memory
> ------------------------------------------------------------------------
> Object :     208  Total  :    1188   Sanity Checks : Off  Total: 4866048
> SlabObj:     208  Full   :    1186   Redzoning     : Off  Used : 4691024
> SlabSiz:    4096  Partial:       0   Poisoning     : Off  Loss :  175024
> Loss   :       0  CpuSlab:       2   Tracking      : Off  Lalig:       0
> Align  :       8  Objects:      19   Tracing       : Off  Lpadd:  171072

So we are using 1188 pages before make

> and after a make kernel & a small delay

2399 pages after make

> on 2.6.26 + my patch

579 * 2 = 1158 (saved 30 pages even before doing anything) before make


> after the make

2025 *2 = 4050 pages which are much more than the 2399 with order 0.
So we are wasting a lot more space. You'd probably need to run slab defrag to get that memory back.

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