Re: [patch 01/11] mm: memcg: consolidate hierarchy iterationprimitives

[KAMEZAWA Hiroyuki]

On Mon, 12 Sep 2011 12:57:18 +0200
Johannes Weiner <jweiner@xxxxxxxxxx> wrote:

> Memory control groups are currently bolted onto the side of
> traditional memory management in places where better integration would
> be preferrable.  To reclaim memory, for example, memory control groups
> maintain their own LRU list and reclaim strategy aside from the global
> per-zone LRU list reclaim.  But an extra list head for each existing
> page frame is expensive and maintaining it requires additional code.
> 
> This patchset disables the global per-zone LRU lists on memory cgroup
> configurations and converts all its users to operate on the per-memory
> cgroup lists instead.  As LRU pages are then exclusively on one list,
> this saves two list pointers for each page frame in the system:
> 
> page_cgroup array size with 4G physical memory
> 
>   vanilla: [    0.000000] allocated 31457280 bytes of page_cgroup
>   patched: [    0.000000] allocated 15728640 bytes of page_cgroup
> 
> At the same time, system performance for various workloads is
> unaffected:
> 
> 100G sparse file cat, 4G physical memory, 10 runs, to test for code
> bloat in the traditional LRU handling and kswapd & direct reclaim
> paths, without/with the memory controller configured in
> 
>   vanilla: 71.603(0.207) seconds
>   patched: 71.640(0.156) seconds
> 
>   vanilla: 79.558(0.288) seconds
>   patched: 77.233(0.147) seconds
> 
> 100G sparse file cat in 1G memory cgroup, 10 runs, to test for code
> bloat in the traditional memory cgroup LRU handling and reclaim path
> 
>   vanilla: 96.844(0.281) seconds
>   patched: 94.454(0.311) seconds
> 
> 4 unlimited memcgs running kbuild -j32 each, 4G physical memory, 500M
> swap on SSD, 10 runs, to test for regressions in kswapd & direct
> reclaim using per-memcg LRU lists with multiple memcgs and multiple
> allocators within each memcg
> 
>   vanilla: 717.722(1.440) seconds [ 69720.100(11600.835) majfaults ]
>   patched: 714.106(2.313) seconds [ 71109.300(14886.186) majfaults ]
> 
> 16 unlimited memcgs running kbuild, 1900M hierarchical limit, 500M
> swap on SSD, 10 runs, to test for regressions in hierarchical memcg
> setups
> 
>   vanilla: 2742.058(1.992) seconds [ 26479.600(1736.737) majfaults ]
>   patched: 2743.267(1.214) seconds [ 27240.700(1076.063) majfaults ]
> 
> This patch:
> 
> There are currently two different implementations of iterating over a
> memory cgroup hierarchy tree.
> 
> Consolidate them into one worker function and base the convenience
> looping-macros on top of it.
> 
> Signed-off-by: Johannes Weiner <jweiner@xxxxxxxxxx>

Seems nice.

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>

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