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Date: Thu, 6 Aug 2020 15:41:28 +0800 From: Alex Shi <alex.shi@...ux.alibaba.com> To: akpm@...ux-foundation.org, mgorman@...hsingularity.net, tj@...nel.org, hughd@...gle.com, khlebnikov@...dex-team.ru, daniel.m.jordan@...cle.com, yang.shi@...ux.alibaba.com, willy@...radead.org, hannes@...xchg.org, lkp@...el.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org, cgroups@...r.kernel.org, shakeelb@...gle.com, iamjoonsoo.kim@....com, richard.weiyang@...il.com, kirill@...temov.name, alexander.duyck@...il.com, rong.a.chen@...el.com Cc: Michal Hocko <mhocko@...nel.org>, Vladimir Davydov <vdavydov.dev@...il.com> Subject: Re: [PATCH v17 17/21] mm/lru: replace pgdat lru_lock with lruvec lock Hi Johannes, Michal, >From page to its lruvec, a few memory access under lock cause extra cost. Would you like to save the per memcg lruvec pointer to page->private? Thanks Alex 在 2020/7/25 下午8:59, Alex Shi 写道: > /** > * mem_cgroup_page_lruvec - return lruvec for isolating/putting an LRU page > * @page: the page > @@ -1215,7 +1228,8 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd > goto out; > } > > - memcg = page->mem_cgroup; > + VM_BUG_ON_PAGE(PageTail(page), page); > + memcg = READ_ONCE(page->mem_cgroup); > /* > * Swapcache readahead pages are added to the LRU - and > * possibly migrated - before they are charged. > @@ -1236,6 +1250,51 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd > return lruvec; > } > > +struct lruvec *lock_page_lruvec(struct page *page) > +{ > + struct lruvec *lruvec; > + struct pglist_data *pgdat = page_pgdat(page); > + > + rcu_read_lock(); > + lruvec = mem_cgroup_page_lruvec(page, pgdat); > + spin_lock(&lruvec->lru_lock); > + rcu_read_unlock(); > + > + lruvec_memcg_debug(lruvec, page); > + > + return lruvec; > +} > +
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