From: Roman Gushchin <guro@xxxxxx> Subject: mm: memcg/slab: cache page number in memcg_(un)charge_slab() There are many places in memcg_charge_slab() and memcg_uncharge_slab() which are calculating the number of pages to charge, css references to grab etc depending on the order of the slab page. Let's simplify the code by calculating it once and caching in the local variable. Link: http://lkml.kernel.org/r/20200109202659.752357-6-guro@xxxxxx Signed-off-by: Roman Gushchin <guro@xxxxxx> Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slab.h | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) --- a/mm/slab.h~mm-memcg-slab-cache-page-number-in-memcg_uncharge_slab +++ a/mm/slab.h @@ -348,6 +348,7 @@ static __always_inline int memcg_charge_ gfp_t gfp, int order, struct kmem_cache *s) { + unsigned int nr_pages = 1 << order; struct mem_cgroup *memcg; struct lruvec *lruvec; int ret; @@ -360,21 +361,21 @@ static __always_inline int memcg_charge_ if (unlikely(!memcg || mem_cgroup_is_root(memcg))) { mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s), - (1 << order)); - percpu_ref_get_many(&s->memcg_params.refcnt, 1 << order); + nr_pages); + percpu_ref_get_many(&s->memcg_params.refcnt, nr_pages); return 0; } - ret = memcg_kmem_charge_memcg(memcg, gfp, 1 << order); + ret = memcg_kmem_charge_memcg(memcg, gfp, nr_pages); if (ret) goto out; lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page)); - mod_lruvec_state(lruvec, cache_vmstat_idx(s), 1 << order); + mod_lruvec_state(lruvec, cache_vmstat_idx(s), nr_pages); /* transer try_charge() page references to kmem_cache */ - percpu_ref_get_many(&s->memcg_params.refcnt, 1 << order); - css_put_many(&memcg->css, 1 << order); + percpu_ref_get_many(&s->memcg_params.refcnt, nr_pages); + css_put_many(&memcg->css, nr_pages); out: css_put(&memcg->css); return ret; @@ -387,6 +388,7 @@ out: static __always_inline void memcg_uncharge_slab(struct page *page, int order, struct kmem_cache *s) { + unsigned int nr_pages = 1 << order; struct mem_cgroup *memcg; struct lruvec *lruvec; @@ -394,15 +396,15 @@ static __always_inline void memcg_unchar memcg = READ_ONCE(s->memcg_params.memcg); if (likely(!mem_cgroup_is_root(memcg))) { lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page)); - mod_lruvec_state(lruvec, cache_vmstat_idx(s), -(1 << order)); - memcg_kmem_uncharge_memcg(memcg, order); + mod_lruvec_state(lruvec, cache_vmstat_idx(s), -nr_pages); + memcg_kmem_uncharge_memcg(memcg, nr_pages); } else { mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s), - -(1 << order)); + -nr_pages); } rcu_read_unlock(); - percpu_ref_put_many(&s->memcg_params.refcnt, 1 << order); + percpu_ref_put_many(&s->memcg_params.refcnt, nr_pages); } extern void slab_init_memcg_params(struct kmem_cache *); _
