Page reclaim at priority 0 will scan the entire LRU as priority 0 is considered to be a near OOM condition. Direct reclaim can reach this priority while still making reclaim progress. This patch avoids reclaiming at priority 0 unless no reclaim progress was made and the page allocator would consider firing the OOM killer. The user-visible impact is that direct reclaim will not easily reach priority 0 and start swapping prematurely.
Signed-off-by: Mel Gorman <[email protected]> --- mm/vmscan.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index fe73724..65f2fbea 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2382,12 +2382,14 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, struct zone *zone; unsigned long writeback_threshold; bool aborted_reclaim; + int min_scan_priority = 1; delayacct_freepages_start(); if (global_reclaim(sc)) count_vm_event(ALLOCSTALL); +rescan: do { vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, sc->priority); @@ -2442,7 +2444,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, WB_REASON_TRY_TO_FREE_PAGES); sc->may_writepage = 1; } - } while (--sc->priority >= 0); + } while (--sc->priority >= min_scan_priority); out: delayacct_freepages_end(); @@ -2466,6 +2468,12 @@ out: if (global_reclaim(sc) && !all_unreclaimable(zonelist, sc)) return 1; + /* If the page allocator is considering OOM, rescan at priority 0 */ + if (min_scan_priority) { + min_scan_priority = 0; + goto rescan; + } + return 0; } -- 1.8.1.4 -- 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/
