On Wed, Dec 20, 2023 at 7:27 AM Dan Schatzberg <schatzberg.dan@xxxxxxxxx> wrote: > > We use the constants 0 and 200 in a few places in the mm code when > referring to the min and max swappiness. This patch adds MIN_SWAPPINESS > and MAX_SWAPPINESS #defines to improve clarity. There are no functional > changes. > > Signed-off-by: Dan Schatzberg <schatzberg.dan@xxxxxxxxx> > --- > include/linux/swap.h | 2 ++ > mm/memcontrol.c | 2 +- > mm/vmscan.c | 14 +++++++------- > 3 files changed, 10 insertions(+), 8 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index f6dd6575b905..e2ab76c25b4a 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -407,6 +407,8 @@ extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order, > > #define MEMCG_RECLAIM_MAY_SWAP (1 << 1) > #define MEMCG_RECLAIM_PROACTIVE (1 << 2) > +#define MIN_SWAPPINESS 0 > +#define MAX_SWAPPINESS 200 > extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, > unsigned long nr_pages, > gfp_t gfp_mask, > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index b226090fd906..fbe9f02dd206 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4337,7 +4337,7 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css, > { > struct mem_cgroup *memcg = mem_cgroup_from_css(css); > > - if (val > 200) > + if (val > MAX_SWAPPINESS) > return -EINVAL; > > if (!mem_cgroup_is_root(memcg)) > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 9dd8977de5a2..d91963e2d47f 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -183,7 +183,7 @@ struct scan_control { > #endif > > /* > - * From 0 .. 200. Higher means more swappy. > + * From 0 .. MAX_SWAPPINESS. Higher means more swappy. > */ > int vm_swappiness = 60; > > @@ -2403,7 +2403,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, > ap = swappiness * (total_cost + 1); > ap /= anon_cost + 1; > > - fp = (200 - swappiness) * (total_cost + 1); > + fp = (MAX_SWAPPINESS - swappiness) * (total_cost + 1); > fp /= file_cost + 1; > > fraction[0] = ap; > @@ -4400,7 +4400,7 @@ static int get_type_to_scan(struct lruvec *lruvec, int swappiness, int *tier_idx > { > int type, tier; > struct ctrl_pos sp, pv; > - int gain[ANON_AND_FILE] = { swappiness, 200 - swappiness }; > + int gain[ANON_AND_FILE] = { swappiness, MAX_SWAPPINESS - swappiness }; > > /* > * Compare the first tier of anon with that of file to determine which > @@ -4436,7 +4436,7 @@ static int isolate_folios(struct lruvec *lruvec, struct scan_control *sc, int sw > /* > * Try to make the obvious choice first. When anon and file are both > * available from the same generation, interpret swappiness 1 as file > - * first and 200 as anon first. > + * first and MAX_SWAPPINESS as anon first. > */ > if (!swappiness) > type = LRU_GEN_FILE; > @@ -4444,7 +4444,7 @@ static int isolate_folios(struct lruvec *lruvec, struct scan_control *sc, int sw > type = LRU_GEN_ANON; > else if (swappiness == 1) > type = LRU_GEN_FILE; > - else if (swappiness == 200) > + else if (swappiness == MAX_SWAPPINESS) > type = LRU_GEN_ANON; > else > type = get_type_to_scan(lruvec, swappiness, &tier); > @@ -5398,9 +5398,9 @@ static int run_cmd(char cmd, int memcg_id, int nid, unsigned long seq, > > lruvec = get_lruvec(memcg, nid); > > - if (swappiness < 0) > + if (swappiness < MIN_SWAPPINESS) > swappiness = get_swappiness(lruvec, sc); > - else if (swappiness > 200) > + else if (swappiness > MAX_SWAPPINESS) > goto done; > > switch (cmd) { > -- > 2.39.3 > Sorry for being late to the party :) Was preoccupied with zswap convos. Hmm these are all the occurrences of 0 and 200 (in the context of swappiness) I can dig out. So, FWIW: Reviewed-by: Nhat Pham <nphamcs@xxxxxxxxx>