Messages in this thread | | | Date | Fri, 14 Dec 2012 10:43:55 -0500 | From | Rik van Riel <> | Subject | Re: [patch 2/8] mm: vmscan: disregard swappiness shortly before going OOM |
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On 12/14/2012 03:37 AM, Michal Hocko wrote:
> I can answer the later. Because memsw comes with its price and > swappiness is much cheaper. On the other hand it makes sense that > swappiness==0 doesn't swap at all. Or do you think we should get back to > _almost_ doesn't swap at all?
swappiness==0 will swap in emergencies, specifically when we have almost no page cache left, we will still swap things out:
if (global_reclaim(sc)) { free = zone_page_state(zone, NR_FREE_PAGES); if (unlikely(file + free <= high_wmark_pages(zone))) { /* * If we have very few page cache pages, force-scan * anon pages. */ fraction[0] = 1; fraction[1] = 0; denominator = 1; goto out;
This makes sense, because people who set swappiness==0 but do have swap space available would probably prefer some emergency swapping over an OOM kill.
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