Message ID | 20210305000002.D171810D@viggo.jf.intel.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | Migrate Pages in lieu of discard | expand |
On Thu, Mar 4, 2021 at 4:01 PM Dave Hansen <dave.hansen@linux.intel.com> wrote: > > > From: Dave Hansen <dave.hansen@linux.intel.com> > > Anonymous pages are kept on their own LRU(s). These lists could > theoretically always be scanned and maintained. But, without swap, > there is currently nothing the kernel can *do* with the results of a > scanned, sorted LRU for anonymous pages. > > A check for '!total_swap_pages' currently serves as a valid check as > to whether anonymous LRUs should be maintained. However, another > method will be added shortly: page demotion. > > Abstract out the 'total_swap_pages' checks into a helper, give it a > logically significant name, and check for the possibility of page > demotion. Reviewed-by: Yang Shi <shy828301@gmail.com> > > Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> > Cc: David Rientjes <rientjes@google.com> > Cc: Huang Ying <ying.huang@intel.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: David Hildenbrand <david@redhat.com> > Cc: osalvador <osalvador@suse.de> > --- > > b/mm/vmscan.c | 28 +++++++++++++++++++++++++--- > 1 file changed, 25 insertions(+), 3 deletions(-) > > diff -puN mm/vmscan.c~mm-vmscan-anon-can-be-aged mm/vmscan.c > --- a/mm/vmscan.c~mm-vmscan-anon-can-be-aged 2021-03-04 15:35:58.935806422 -0800 > +++ b/mm/vmscan.c 2021-03-04 15:35:58.942806422 -0800 > @@ -2517,6 +2517,26 @@ out: > } > } > > +/* > + * Anonymous LRU management is a waste if there is > + * ultimately no way to reclaim the memory. > + */ > +bool anon_should_be_aged(struct lruvec *lruvec) > +{ > + struct pglist_data *pgdat = lruvec_pgdat(lruvec); > + > + /* Aging the anon LRU is valuable if swap is present: */ > + if (total_swap_pages > 0) > + return true; > + > + /* Also valuable if anon pages can be demoted: */ > + if (next_demotion_node(pgdat->node_id) >= 0) > + return true; > + > + /* No way to reclaim anon pages. Should not age anon LRUs: */ > + return false; > +} > + > static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) > { > unsigned long nr[NR_LRU_LISTS]; > @@ -2626,7 +2646,8 @@ static void shrink_lruvec(struct lruvec > * Even if we did not try to evict anon pages at all, we want to > * rebalance the anon lru active/inactive ratio. > */ > - if (total_swap_pages && inactive_is_low(lruvec, LRU_INACTIVE_ANON)) > + if (anon_should_be_aged(lruvec) && > + inactive_is_low(lruvec, LRU_INACTIVE_ANON)) > shrink_active_list(SWAP_CLUSTER_MAX, lruvec, > sc, LRU_ACTIVE_ANON); > } > @@ -3455,10 +3476,11 @@ static void age_active_anon(struct pglis > struct mem_cgroup *memcg; > struct lruvec *lruvec; > > - if (!total_swap_pages) > + lruvec = mem_cgroup_lruvec(NULL, pgdat); > + > + if (!anon_should_be_aged(lruvec)) > return; > > - lruvec = mem_cgroup_lruvec(NULL, pgdat); > if (!inactive_is_low(lruvec, LRU_INACTIVE_ANON)) > return; > > _ >
Dave Hansen <dave.hansen@linux.intel.com> wrote: > From: Dave Hansen <dave.hansen@linux.intel.com> > > Anonymous pages are kept on their own LRU(s). These lists could > theoretically always be scanned and maintained. But, without swap, > there is currently nothing the kernel can *do* with the results of a > scanned, sorted LRU for anonymous pages. > > A check for '!total_swap_pages' currently serves as a valid check as > to whether anonymous LRUs should be maintained. However, another > method will be added shortly: page demotion. > > Abstract out the 'total_swap_pages' checks into a helper, give it a > logically significant name, and check for the possibility of page > demotion. Reviewed-by: Greg Thelen <gthelen@google.com> > Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> > Cc: David Rientjes <rientjes@google.com> > Cc: Huang Ying <ying.huang@intel.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: David Hildenbrand <david@redhat.com> > Cc: osalvador <osalvador@suse.de> > --- > > b/mm/vmscan.c | 28 +++++++++++++++++++++++++--- > 1 file changed, 25 insertions(+), 3 deletions(-) > > diff -puN mm/vmscan.c~mm-vmscan-anon-can-be-aged mm/vmscan.c > --- a/mm/vmscan.c~mm-vmscan-anon-can-be-aged 2021-03-04 15:35:58.935806422 -0800 > +++ b/mm/vmscan.c 2021-03-04 15:35:58.942806422 -0800 > @@ -2517,6 +2517,26 @@ out: > } > } > > +/* > + * Anonymous LRU management is a waste if there is > + * ultimately no way to reclaim the memory. > + */ > +bool anon_should_be_aged(struct lruvec *lruvec) Should this be static? > +{ > + struct pglist_data *pgdat = lruvec_pgdat(lruvec); > + > + /* Aging the anon LRU is valuable if swap is present: */ > + if (total_swap_pages > 0) > + return true; > + > + /* Also valuable if anon pages can be demoted: */ > + if (next_demotion_node(pgdat->node_id) >= 0) > + return true; > + > + /* No way to reclaim anon pages. Should not age anon LRUs: */ > + return false; > +} > + > static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) > { > unsigned long nr[NR_LRU_LISTS]; > @@ -2626,7 +2646,8 @@ static void shrink_lruvec(struct lruvec > * Even if we did not try to evict anon pages at all, we want to > * rebalance the anon lru active/inactive ratio. > */ > - if (total_swap_pages && inactive_is_low(lruvec, LRU_INACTIVE_ANON)) > + if (anon_should_be_aged(lruvec) && > + inactive_is_low(lruvec, LRU_INACTIVE_ANON)) > shrink_active_list(SWAP_CLUSTER_MAX, lruvec, > sc, LRU_ACTIVE_ANON); > } > @@ -3455,10 +3476,11 @@ static void age_active_anon(struct pglis > struct mem_cgroup *memcg; > struct lruvec *lruvec; > > - if (!total_swap_pages) > + lruvec = mem_cgroup_lruvec(NULL, pgdat); > + > + if (!anon_should_be_aged(lruvec)) > return; > > - lruvec = mem_cgroup_lruvec(NULL, pgdat); > if (!inactive_is_low(lruvec, LRU_INACTIVE_ANON)) > return; > > _
diff -puN mm/vmscan.c~mm-vmscan-anon-can-be-aged mm/vmscan.c --- a/mm/vmscan.c~mm-vmscan-anon-can-be-aged 2021-03-04 15:35:58.935806422 -0800 +++ b/mm/vmscan.c 2021-03-04 15:35:58.942806422 -0800 @@ -2517,6 +2517,26 @@ out: } } +/* + * Anonymous LRU management is a waste if there is + * ultimately no way to reclaim the memory. + */ +bool anon_should_be_aged(struct lruvec *lruvec) +{ + struct pglist_data *pgdat = lruvec_pgdat(lruvec); + + /* Aging the anon LRU is valuable if swap is present: */ + if (total_swap_pages > 0) + return true; + + /* Also valuable if anon pages can be demoted: */ + if (next_demotion_node(pgdat->node_id) >= 0) + return true; + + /* No way to reclaim anon pages. Should not age anon LRUs: */ + return false; +} + static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) { unsigned long nr[NR_LRU_LISTS]; @@ -2626,7 +2646,8 @@ static void shrink_lruvec(struct lruvec * Even if we did not try to evict anon pages at all, we want to * rebalance the anon lru active/inactive ratio. */ - if (total_swap_pages && inactive_is_low(lruvec, LRU_INACTIVE_ANON)) + if (anon_should_be_aged(lruvec) && + inactive_is_low(lruvec, LRU_INACTIVE_ANON)) shrink_active_list(SWAP_CLUSTER_MAX, lruvec, sc, LRU_ACTIVE_ANON); } @@ -3455,10 +3476,11 @@ static void age_active_anon(struct pglis struct mem_cgroup *memcg; struct lruvec *lruvec; - if (!total_swap_pages) + lruvec = mem_cgroup_lruvec(NULL, pgdat); + + if (!anon_should_be_aged(lruvec)) return; - lruvec = mem_cgroup_lruvec(NULL, pgdat); if (!inactive_is_low(lruvec, LRU_INACTIVE_ANON)) return;