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. -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/