3.2-stable review patch. If anyone has any objections, please let me know.
------------------ From: Satoru Moriya <[email protected]> commit fe35004fbf9eaf67482b074a2e032abb9c89b1dd upstream. 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 in 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)). Signed-off-by: Satoru Moriya <[email protected]> Acked-by: Minchan Kim <[email protected]> Reviewed-by: Rik van Riel <[email protected]> Acked-by: Jerome Marchand <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> [bwh: Backported to 3.2: - Adjust context - vmscan_swappiness() does not have a zone parameter] Signed-off-by: Ben Hutchings <[email protected]> --- mm/vmscan.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1977,10 +1977,10 @@ static void get_scan_count(struct zone * * proportional to the fraction of recently scanned pages on * each list that were recently referenced and in active use. */ - ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); + ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); ap /= reclaim_stat->recent_rotated[0] + 1; - fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); + fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); fp /= reclaim_stat->recent_rotated[1] + 1; spin_unlock_irq(&zone->lru_lock); @@ -1993,7 +1993,7 @@ out: unsigned long scan; scan = zone_nr_lru_pages(zone, sc, l); - if (priority || noswap) { + if (priority || noswap || !vmscan_swappiness(sc)) { scan >>= priority; if (!scan && force_scan) scan = SWAP_CLUSTER_MAX; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
