From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 377DEC48BC2 for ; Mon, 28 Jun 2021 02:56:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1F4EB61C2E for ; Mon, 28 Jun 2021 02:56:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232050AbhF1C7R (ORCPT ); Sun, 27 Jun 2021 22:59:17 -0400 Received: from mga07.intel.com ([134.134.136.100]:56857 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231678AbhF1C7Q (ORCPT ); Sun, 27 Jun 2021 22:59:16 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10028"; a="271737095" X-IronPort-AV: E=Sophos;i="5.83,304,1616482800"; d="scan'208";a="271737095" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jun 2021 19:56:51 -0700 X-IronPort-AV: E=Sophos;i="5.83,304,1616482800"; d="scan'208";a="419008053" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.239.159.119]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jun 2021 19:56:46 -0700 From: "Huang, Ying" To: Wei Xu Cc: Linux MM , Linux Kernel Mailing List , Keith Busch , Dave Hansen , Yang Shi , Michal Hocko , Zi Yan , David Rientjes , Dan Williams , David Hildenbrand Subject: Re: [PATCH -V9 7/9] mm/vmscan: Consider anonymous pages without swap References: <20210625073204.1005986-1-ying.huang@intel.com> <20210625073204.1005986-8-ying.huang@intel.com> Date: Mon, 28 Jun 2021 10:56:44 +0800 In-Reply-To: (Wei Xu's message of "Fri, 25 Jun 2021 17:02:25 -0700") Message-ID: <874kdig0ib.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Wei Xu writes: > On Fri, Jun 25, 2021 at 12:33 AM Huang Ying wrote: >> >> From: Keith Busch >> >> Reclaim anonymous pages if a migration path is available now that >> demotion provides a non-swap recourse for reclaiming anon pages. >> >> Note that this check is subtly different from the >> anon_should_be_aged() checks. This mechanism checks whether a >> specific page in a specific context *can* actually be reclaimed, given >> current swap space and cgroup limits >> >> anon_should_be_aged() is a much simpler and more preliminary check >> which just says whether there is a possibility of future reclaim. >> >> Cc: Keith Busch >> Signed-off-by: Dave Hansen >> Signed-off-by: "Huang, Ying" >> Reviewed-by: Yang Shi >> Cc: Michal Hocko >> Cc: Zi Yan >> Cc: Wei Xu >> Cc: David Rientjes >> Cc: Dan Williams >> Cc: David Hildenbrand >> >> -- >> >> Changes since 20210618: >> * Consider whether demotion is disabled >> >> Changes from Dave 202010: >> * remove 'total_swap_pages' modification >> >> Changes from Dave 202006: >> * rename reclaim_anon_pages()->can_reclaim_anon_pages() >> >> Note: Keith's Intel SoB is commented out because he is no >> longer at Intel and his @intel.com mail will bounce. >> --- >> mm/vmscan.c | 37 ++++++++++++++++++++++++++++++++++--- >> 1 file changed, 34 insertions(+), 3 deletions(-) >> >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index 55f6192b2a51..fce43c7970d7 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -519,6 +519,36 @@ static long add_nr_deferred(long nr, struct shrinker *shrinker, >> return atomic_long_add_return(nr, &shrinker->nr_deferred[nid]); >> } >> >> +static inline bool can_reclaim_anon_pages(struct mem_cgroup *memcg, >> + int node_id, >> + struct scan_control *sc) >> +{ >> + if (memcg == NULL) { >> + /* >> + * For non-memcg reclaim, is there >> + * space in any swap device? >> + */ >> + if (get_nr_swap_pages() > 0) >> + return true; >> + } else { >> + /* Is the memcg below its swap limit? */ >> + if (mem_cgroup_get_nr_swap_pages(memcg) > 0) >> + return true; >> + } >> + >> + /* >> + * The page can not be swapped. >> + * >> + * Can it be reclaimed from this node via demotion? >> + */ >> + if ((!sc || !sc->no_demotion) && >> + next_demotion_node(node_id) != NUMA_NO_NODE) >> + return true; > > It is better to abstract these checks into a function, e.g. > can_demote_anon_pages(), to share with anon_can_be_aged(). Thanks! This is a really good idea! The function can be used by shrink_page_list() too. So code duplication is reduced greatly! Will do that in the next version. Best Regards, Huang, Ying >> + /* No way to reclaim anon pages */ >> + return false; >> +} >> + >> /* >> * This misses isolated pages which are not accounted for to save counters. >> * As the data only determines if reclaim or compaction continues, it is >> @@ -530,7 +560,7 @@ unsigned long zone_reclaimable_pages(struct zone *zone) >> >> nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) + >> zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE); >> - if (get_nr_swap_pages() > 0) >> + if (can_reclaim_anon_pages(NULL, zone_to_nid(zone), NULL)) >> nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) + >> zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON); >> >> @@ -2531,6 +2561,7 @@ enum scan_balance { >> static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, >> unsigned long *nr) >> { >> + struct pglist_data *pgdat = lruvec_pgdat(lruvec); >> struct mem_cgroup *memcg = lruvec_memcg(lruvec); >> unsigned long anon_cost, file_cost, total_cost; >> int swappiness = mem_cgroup_swappiness(memcg); >> @@ -2541,7 +2572,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, >> enum lru_list lru; >> >> /* If we have no swap space, do not bother scanning anon pages. */ >> - if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) { >> + if (!sc->may_swap || !can_reclaim_anon_pages(memcg, pgdat->node_id, sc)) { >> scan_balance = SCAN_FILE; >> goto out; >> } >> @@ -2916,7 +2947,7 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat, >> */ >> pages_for_compaction = compact_gap(sc->order); >> inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE); >> - if (get_nr_swap_pages() > 0) >> + if (can_reclaim_anon_pages(NULL, pgdat->node_id, sc)) >> inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON); >> >> return inactive_lru_pages > pages_for_compaction; >> -- >> 2.30.2 >>