Hello, On Mon, Jun 09, 2014 at 09:27:16PM +0800, Chen Yucong wrote: > Via https://lkml.org/lkml/2013/4/10/334 , we can find that recording the > original scan targets introduces extra 40 bytes on the stack. This patch > is able to avoid this situation and the call to memcpy(). At the same time, > it does not change the relative design idea. > > ratio = original_nr_file / original_nr_anon; > > If (nr_file > nr_anon), then ratio = (nr_file - x) / nr_anon. > x = nr_file - ratio * nr_anon; > > if (nr_file <= nr_anon), then ratio = nr_file / (nr_anon - x). > x = nr_anon - nr_file / ratio;
Nice cleanup! Below one nitpick. > > Signed-off-by: Chen Yucong <[email protected]> > --- > mm/vmscan.c | 28 +++++++++------------------- > 1 file changed, 9 insertions(+), 19 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index a8ffe4e..daaf89c 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2057,8 +2057,7 @@ out: > static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) > { > unsigned long nr[NR_LRU_LISTS]; > - unsigned long targets[NR_LRU_LISTS]; > - unsigned long nr_to_scan; > + unsigned long nr_to_scan, ratio; > enum lru_list lru; > unsigned long nr_reclaimed = 0; > unsigned long nr_to_reclaim = sc->nr_to_reclaim; > @@ -2067,8 +2066,8 @@ static void shrink_lruvec(struct lruvec *lruvec, struct > scan_control *sc) > > get_scan_count(lruvec, sc, nr); > > - /* Record the original scan target for proportional adjustments later */ > - memcpy(targets, nr, sizeof(nr)); > + ratio = (nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE] + 1) / > + (nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON] + 1); > > /* > * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal > @@ -2088,7 +2087,6 @@ static void shrink_lruvec(struct lruvec *lruvec, struct > scan_control *sc) > while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || > nr[LRU_INACTIVE_FILE]) { > unsigned long nr_anon, nr_file, percentage; > - unsigned long nr_scanned; > > for_each_evictable_lru(lru) { > if (nr[lru]) { > @@ -2123,15 +2121,13 @@ static void shrink_lruvec(struct lruvec *lruvec, > struct scan_control *sc) > break; > > if (nr_file > nr_anon) { > - unsigned long scan_target = targets[LRU_INACTIVE_ANON] + > - targets[LRU_ACTIVE_ANON] + 1; > + nr_to_scan = nr_file - ratio * nr_anon; > + percentage = nr[LRU_FILE] * 100 / nr_file; > lru = LRU_BASE; > - percentage = nr_anon * 100 / scan_target; > } else { > - unsigned long scan_target = targets[LRU_INACTIVE_FILE] + > - targets[LRU_ACTIVE_FILE] + 1; > + nr_to_scan = nr_anon - nr_file / ratio; > + percentage = nr[LRU_BASE] * 100 / nr_anon; If both nr_file and nr_anon are zero, then the nr_anon could be zero if HugePage are reclaimed so that it could pass the below check if (nr_reclaimed < nr_to_reclaim || scan_adjusted) > lru = LRU_FILE; > - percentage = nr_file * 100 / scan_target; > } > > /* Stop scanning the smaller of the LRU */ > @@ -2143,14 +2139,8 @@ static void shrink_lruvec(struct lruvec *lruvec, > struct scan_control *sc) > * scan target and the percentage scanning already complete > */ > lru = (lru == LRU_FILE) ? LRU_BASE : LRU_FILE; > - nr_scanned = targets[lru] - nr[lru]; > - nr[lru] = targets[lru] * (100 - percentage) / 100; > - nr[lru] -= min(nr[lru], nr_scanned); > - > - lru += LRU_ACTIVE; > - nr_scanned = targets[lru] - nr[lru]; > - nr[lru] = targets[lru] * (100 - percentage) / 100; > - nr[lru] -= min(nr[lru], nr_scanned); > + nr[lru] = nr_to_scan * percentage / 100; > + nr[lru + LRU_ACTIVE] = nr_to_scan - nr[lru]; > > scan_adjusted = true; > } > -- > 1.7.10.4 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to [email protected]. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"[email protected]";> [email protected] </a> -- Kind regards, Minchan Kim -- 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/
