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=-2.3 required=3.0 tests=BAYES_00,FAKE_REPLY_C, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 4B9C1C433E0 for ; Tue, 16 Mar 2021 02:09:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CF8BB64EFD for ; Tue, 16 Mar 2021 02:09:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF8BB64EFD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5A6036B006C; Mon, 15 Mar 2021 22:09:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5558A6B006E; Mon, 15 Mar 2021 22:09:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3F8206B0070; Mon, 15 Mar 2021 22:09:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0066.hostedemail.com [216.40.44.66]) by kanga.kvack.org (Postfix) with ESMTP id 221B86B006C for ; Mon, 15 Mar 2021 22:09:02 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id DEED1180AD830 for ; Tue, 16 Mar 2021 02:09:01 +0000 (UTC) X-FDA: 77924104482.02.A5D7EA5 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by imf01.hostedemail.com (Postfix) with ESMTP id EBEA12000380 for ; Tue, 16 Mar 2021 02:09:00 +0000 (UTC) IronPort-SDR: NoMFFN+KJcRzOVOiKmDDALO/miirfUR5Tt/OqcEua7l059+ZZRnuXYgOmBGfBkq4HzB5gYwSkO domrRVt3CzsQ== X-IronPort-AV: E=McAfee;i="6000,8403,9924"; a="169101065" X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="169101065" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Mar 2021 19:08:59 -0700 IronPort-SDR: SPTHSj6HkgQoZ3Q7lopQ61Jk45aLfkIvYBbRHSiDmI95R2J68a3jyJ6r2bZ2ulF4puTHOcPVWu eYViBXSN/z4Q== X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="388305768" Received: from unknown (HELO yhuang6-desk1.ccr.corp.intel.com) ([10.239.13.1]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Mar 2021 19:08:55 -0700 From: "Huang, Ying" To: Yu Zhao Cc: linux-mm@kvack.org, Alex Shi , Andrew Morton , Dave Hansen , Hillf Danton , Johannes Weiner , Joonsoo Kim , Matthew Wilcox , Mel Gorman , Michal Hocko , Roman Gushchin , Vlastimil Babka , Wei Yang , Yang Shi , linux-kernel@vger.kernel.org, page-reclaim@google.com Subject: Re: [PATCH v1 10/14] mm: multigenerational lru: core Date: Tue, 16 Mar 2021 10:08:51 +0800 Message-ID: <87im5rsvd8.fsf@yhuang6-desk1.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 X-Stat-Signature: fbtu8ej51epxoqdcgfzrfu951g173b6m X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: EBEA12000380 Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf01; identity=mailfrom; envelope-from=""; helo=mga17.intel.com; client-ip=192.55.52.151 X-HE-DKIM-Result: none/none X-HE-Tag: 1615860540-618273 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Yu Zhao writes: [snip] > +/* Main function used by foreground, background and user-triggered aging. */ > +static bool walk_mm_list(struct lruvec *lruvec, unsigned long next_seq, > + struct scan_control *sc, int swappiness) > +{ > + bool last; > + struct mm_struct *mm = NULL; > + int nid = lruvec_pgdat(lruvec)->node_id; > + struct mem_cgroup *memcg = lruvec_memcg(lruvec); > + struct lru_gen_mm_list *mm_list = get_mm_list(memcg); > + > + VM_BUG_ON(next_seq > READ_ONCE(lruvec->evictable.max_seq)); > + > + /* > + * For each walk of the mm list of a memcg, we decrement the priority > + * of its lruvec. For each walk of memcgs in kswapd, we increment the > + * priorities of all lruvecs. > + * > + * So if this lruvec has a higher priority (smaller value), it means > + * other concurrent reclaimers (global or memcg reclaim) have walked > + * its mm list. Skip it for this priority to balance the pressure on > + * all memcgs. > + */ > +#ifdef CONFIG_MEMCG > + if (!mem_cgroup_disabled() && !cgroup_reclaim(sc) && > + sc->priority > atomic_read(&lruvec->evictable.priority)) > + return false; > +#endif > + > + do { > + last = get_next_mm(lruvec, next_seq, swappiness, &mm); > + if (mm) > + walk_mm(lruvec, mm, swappiness); > + > + cond_resched(); > + } while (mm); It appears that we need to scan the whole address space of multiple processes in this loop? If so, I have some concerns about the duration of the function. Do you have some number of the distribution of the duration of the function? And may be the number of mm_struct and the number of pages scanned. In comparison, in the traditional LRU algorithm, for each round, only a small subset of the whole physical memory is scanned. Best Regards, Huang, Ying > + > + if (!last) { > + /* foreground aging prefers not to wait unless "necessary" */ > + if (!current_is_kswapd() && sc->priority < DEF_PRIORITY - 2) > + wait_event_killable(mm_list->nodes[nid].wait, > + next_seq < READ_ONCE(lruvec->evictable.max_seq)); > + > + return next_seq < READ_ONCE(lruvec->evictable.max_seq); > + } > + > + VM_BUG_ON(next_seq != READ_ONCE(lruvec->evictable.max_seq)); > + > + inc_max_seq(lruvec); > + > +#ifdef CONFIG_MEMCG > + if (!mem_cgroup_disabled()) > + atomic_add_unless(&lruvec->evictable.priority, -1, 0); > +#endif > + > + /* order against inc_max_seq() */ > + smp_mb(); > + /* either we see any waiters or they will see updated max_seq */ > + if (waitqueue_active(&mm_list->nodes[nid].wait)) > + wake_up_all(&mm_list->nodes[nid].wait); > + > + wakeup_flusher_threads(WB_REASON_VMSCAN); > + > + return true; > +} > + [snip] Best Regards, Huang, Ying