Messages in this thread |  | | | Date | Mon, 5 Mar 2012 22:56:02 +0100 | | From | Johannes Weiner <> | | Subject | Re: [RFC][PATCH] avoid swapping out with swappiness==0 |
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On Fri, Mar 02, 2012 at 12:36:40PM -0500, Satoru Moriya wrote: > Sometimes we'd like to avoid swapping out anonymous memory > in particular, avoid swapping out pages of important process or > process groups while there is a reasonable amount of pagecache > on RAM so that we can satisfy our customers' requirements. > > OTOH, we can control how aggressive the kernel will swap memory pages > with /proc/sys/vm/swappiness for global and > /sys/fs/cgroup/memory/memory.swappiness for each memcg. > > But with current reclaim implementation, the kernel may swap out > even if we set swappiness==0 and there is pagecache on RAM. > > This patch changes the behavior with swappiness==0. If we set > swappiness==0, the kernel does not swap out completely > (for global reclaim until the amount of free pages and filebacked > pages in a zone has been reduced to something very very small > (nr_free + nr_filebacked < high watermark)). > > Any comments are welcome.
Last time I tried that (getting rid of sc->may_swap, using !swappiness), it was rejected it as there were users who relied on swapping very slowly with this setting.
KOSAKI-san, do I remember correctly? Do you still think it's an issue?
Personally, I still think it's illogical that !swappiness allows swapping and would love to see this patch go in.
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