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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21523C433F5 for ; Thu, 7 Apr 2022 03:16:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239936AbiDGDSn (ORCPT ); Wed, 6 Apr 2022 23:18:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240016AbiDGDS1 (ORCPT ); Wed, 6 Apr 2022 23:18:27 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2FC02E124E for ; Wed, 6 Apr 2022 20:16:12 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-2eb8b94ad35so38570367b3.9 for ; Wed, 06 Apr 2022 20:16:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc:content-transfer-encoding; bh=Artd3VgmPfRvgJSGx+z1Kh9KEzM48iDqoWnEYSArpAs=; b=RXSD1P20FecKhU9EvkEbe8qQkdfzqFyaZHASZakqNZpIs9fyF0EvUnJ2YTOIhkeXOE tJztkP9xyGj6ZEPMFdDptYgmHHfOJEOkPjmxlKMWBV6/wbWDZ6QgyYPhZ0RIHOEJrZb1 Rad+U2zx4t8ASeZdZ07fVR/TwXApI0p8rfxN6Adx5eOAMJryyGoGNQG7Acc7UUHUYiH0 9sVKxpnURKJmZCokKSnmE9Qht71V0tjrfRVa1NkRGaSb3POt9zoueAT0J/EH/q+B4uVW 7s5wAAmBIfP04+WaEqS9xmPcfj5TCuQArZFhC/mD2A1QN7FXDHd9opM6upZI78Fv6LVB sH3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc:content-transfer-encoding; bh=Artd3VgmPfRvgJSGx+z1Kh9KEzM48iDqoWnEYSArpAs=; b=PEJA2K/+QPlSWNgS9FP1naZCaLF1xxnkaBqn16DCL85Eij2VIfVjP2CGof0o6Bdly1 13oC4Ci1MEvqfl1jR4gCReB1RIFzfQj3Qkc0Sl68RzHySU/krRrN4BQ/UyjpNLBZvqi5 Wr1DOPvew4haPidPi9YQVQBHH9j9sVYu4sGztmT+sgRpYjxdE30ISDk4Eu4Gd1j/HF6U Hkrfwu1Y32E2S6Tq4B28s2Fkev8gI6HyEQJLOaLHWmRQqflrLB2PvVdTO+eHobR0jEhl ZEo9BPHqC4IJMYGTlPqzgGTv4w7KlvidnUX1XK+jiZFMGMbF+Jpr8eh32qpGQdCSCR4u EIKg== X-Gm-Message-State: AOAM533JWGfgCZZkGvoply0UYbTHVICfDlyYlzvfqoJYW2BAAdqMCERB 2S3JDLUfa/c+RtzDvb8wlDhxO97jbH8= X-Google-Smtp-Source: ABdhPJwFwHRQ5a4Ww5IVXUAiiZXrkd1a8KUZIIAq0wSKl1tfIV4Z7oQsyhEIU6/ovaLsXaPu7ShP1QBdOt4= X-Received: from yuzhao.bld.corp.google.com ([2620:15c:183:200:9ea2:c755:ae22:6862]) (user=yuzhao job=sendgmr) by 2002:a81:a50b:0:b0:2eb:9a58:cfda with SMTP id u11-20020a81a50b000000b002eb9a58cfdamr10031842ywg.464.1649301371926; Wed, 06 Apr 2022 20:16:11 -0700 (PDT) Date: Wed, 6 Apr 2022 21:15:22 -0600 In-Reply-To: <20220407031525.2368067-1-yuzhao@google.com> Message-Id: <20220407031525.2368067-11-yuzhao@google.com> Mime-Version: 1.0 References: <20220407031525.2368067-1-yuzhao@google.com> X-Mailer: git-send-email 2.35.1.1094.g7c7d902a7c-goog Subject: [PATCH v10 10/14] mm: multi-gen LRU: kill switch From: Yu Zhao To: Stephen Rothwell , linux-mm@kvack.org Cc: Andi Kleen , Andrew Morton , Aneesh Kumar , Barry Song <21cnbao@gmail.com>, Catalin Marinas , Dave Hansen , Hillf Danton , Jens Axboe , Jesse Barnes , Johannes Weiner , Jonathan Corbet , Linus Torvalds , Matthew Wilcox , Mel Gorman , Michael Larabel , Michal Hocko , Mike Rapoport , Rik van Riel , Vlastimil Babka , Will Deacon , Ying Huang , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, page-reclaim@google.com, x86@kernel.org, Yu Zhao , Brian Geffon , Jan Alexander Steffens , Oleksandr Natalenko , Steven Barrett , Suleiman Souhlal , Daniel Byrne , Donald Carr , "=?UTF-8?q?Holger=20Hoffst=C3=A4tte?=" , Konstantin Kharlamov , Shuang Zhai , Sofia Trinh , Vaibhav Jain Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Add /sys/kernel/mm/lru_gen/enabled as a kill switch. Components that can be disabled include: 0x0001: the multi-gen LRU core 0x0002: walking page table, when arch_has_hw_pte_young() returns true 0x0004: clearing the accessed bit in non-leaf PMD entries, when CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG=3Dy [yYnN]: apply to all the components above E.g., echo y >/sys/kernel/mm/lru_gen/enabled cat /sys/kernel/mm/lru_gen/enabled 0x0007 echo 5 >/sys/kernel/mm/lru_gen/enabled cat /sys/kernel/mm/lru_gen/enabled 0x0005 NB: the page table walks happen on the scale of seconds under heavy memory pressure, in which case the mmap_lock contention is a lesser concern, compared with the LRU lock contention and the I/O congestion. So far the only well-known case of the mmap_lock contention happens on Android, due to Scudo [1] which allocates several thousand VMAs for merely a few hundred MBs. The SPF and the Maple Tree also have provided their own assessments [2][3]. However, if walking page tables does worsen the mmap_lock contention, the kill switch can be used to disable it. In this case the multi-gen LRU will suffer a minor performance degradation, as shown previously. Clearing the accessed bit in non-leaf PMD entries can also be disabled, since this behavior was not tested on x86 varieties other than Intel and AMD. [1] https://source.android.com/devices/tech/debug/scudo [2] https://lore.kernel.org/r/20220128131006.67712-1-michel@lespinasse.org/ [3] https://lore.kernel.org/r/20220202024137.2516438-1-Liam.Howlett@oracle.= com/ Signed-off-by: Yu Zhao Acked-by: Brian Geffon Acked-by: Jan Alexander Steffens (heftig) Acked-by: Oleksandr Natalenko Acked-by: Steven Barrett Acked-by: Suleiman Souhlal Tested-by: Daniel Byrne Tested-by: Donald Carr Tested-by: Holger Hoffst=C3=A4tte Tested-by: Konstantin Kharlamov Tested-by: Shuang Zhai Tested-by: Sofia Trinh Tested-by: Vaibhav Jain --- include/linux/cgroup.h | 15 +- include/linux/mm_inline.h | 12 +- include/linux/mmzone.h | 9 ++ kernel/cgroup/cgroup-internal.h | 1 - mm/Kconfig | 6 + mm/vmscan.c | 238 +++++++++++++++++++++++++++++++- 6 files changed, 272 insertions(+), 9 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 0d1ada8968d7..1bc0cabf993f 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -432,6 +432,18 @@ static inline void cgroup_put(struct cgroup *cgrp) css_put(&cgrp->self); } =20 +extern struct mutex cgroup_mutex; + +static inline void cgroup_lock(void) +{ + mutex_lock(&cgroup_mutex); +} + +static inline void cgroup_unlock(void) +{ + mutex_unlock(&cgroup_mutex); +} + /** * task_css_set_check - obtain a task's css_set with extra access conditio= ns * @task: the task to obtain css_set for @@ -446,7 +458,6 @@ static inline void cgroup_put(struct cgroup *cgrp) * as locks used during the cgroup_subsys::attach() methods. */ #ifdef CONFIG_PROVE_RCU -extern struct mutex cgroup_mutex; extern spinlock_t css_set_lock; #define task_css_set_check(task, __c) \ rcu_dereference_check((task)->cgroups, \ @@ -708,6 +719,8 @@ struct cgroup; static inline u64 cgroup_id(const struct cgroup *cgrp) { return 1; } static inline void css_get(struct cgroup_subsys_state *css) {} static inline void css_put(struct cgroup_subsys_state *css) {} +static inline void cgroup_lock(void) {} +static inline void cgroup_unlock(void) {} static inline int cgroup_attach_task_all(struct task_struct *from, struct task_struct *t) { return 0; } static inline int cgroupstats_build(struct cgroupstats *stats, diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index 8a8f87b72540..352862af2669 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -106,7 +106,15 @@ static __always_inline enum lru_list folio_lru_list(st= ruct folio *folio) =20 static inline bool lru_gen_enabled(void) { - return true; +#ifdef CONFIG_LRU_GEN_ENABLED + DECLARE_STATIC_KEY_TRUE(lru_gen_caps[NR_LRU_GEN_CAPS]); + + return static_branch_likely(&lru_gen_caps[LRU_GEN_CORE]); +#else + DECLARE_STATIC_KEY_FALSE(lru_gen_caps[NR_LRU_GEN_CAPS]); + + return static_branch_unlikely(&lru_gen_caps[LRU_GEN_CORE]); +#endif } =20 static inline bool lru_gen_in_fault(void) @@ -196,7 +204,7 @@ static inline bool lru_gen_add_folio(struct lruvec *lru= vec, struct folio *folio, int zone =3D folio_zonenum(folio); struct lru_gen_struct *lrugen =3D &lruvec->lrugen; =20 - if (folio_test_unevictable(folio)) + if (folio_test_unevictable(folio) || !lrugen->enabled) return false; /* * There are three common cases for this page: diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index a1a99971ff9c..525dbf5e14fa 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -384,6 +384,13 @@ enum { LRU_GEN_FILE, }; =20 +enum { + LRU_GEN_CORE, + LRU_GEN_MM_WALK, + LRU_GEN_NONLEAF_YOUNG, + NR_LRU_GEN_CAPS +}; + #define MIN_LRU_BATCH BITS_PER_LONG #define MAX_LRU_BATCH (MIN_LRU_BATCH * 128) =20 @@ -422,6 +429,8 @@ struct lru_gen_struct { /* can be modified without holding the LRU lock */ atomic_long_t evicted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS]; atomic_long_t refaulted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS]; + /* whether the multi-gen LRU is enabled */ + bool enabled; }; =20 enum { diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-interna= l.h index 6e36e854b512..929ed3bf1a7c 100644 --- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -165,7 +165,6 @@ struct cgroup_mgctx { #define DEFINE_CGROUP_MGCTX(name) \ struct cgroup_mgctx name =3D CGROUP_MGCTX_INIT(name) =20 -extern struct mutex cgroup_mutex; extern spinlock_t css_set_lock; extern struct cgroup_subsys *cgroup_subsys[]; extern struct list_head cgroup_roots; diff --git a/mm/Kconfig b/mm/Kconfig index c40777d098a8..b55546191369 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -918,6 +918,12 @@ config LRU_GEN help A high performance LRU implementation to overcommit memory. =20 +config LRU_GEN_ENABLED + bool "Enable by default" + depends on LRU_GEN + help + This option enables the multi-gen LRU by default. + config LRU_GEN_STATS bool "Full stats for debugging" depends on LRU_GEN diff --git a/mm/vmscan.c b/mm/vmscan.c index 0663f1a3f72a..33845796d100 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -52,6 +52,7 @@ #include #include #include +#include =20 #include #include @@ -2989,6 +2990,12 @@ static bool can_age_anon_pages(struct pglist_data *p= gdat, =20 #ifdef CONFIG_LRU_GEN =20 +#ifdef CONFIG_LRU_GEN_ENABLED +DEFINE_STATIC_KEY_ARRAY_TRUE(lru_gen_caps, NR_LRU_GEN_CAPS); +#else +DEFINE_STATIC_KEY_ARRAY_FALSE(lru_gen_caps, NR_LRU_GEN_CAPS); +#endif + /*************************************************************************= ***** * shorthand helpers *************************************************************************= *****/ @@ -3025,6 +3032,15 @@ static int folio_lru_tier(struct folio *folio) return lru_tier_from_refs(refs); } =20 +static bool get_cap(int cap) +{ +#ifdef CONFIG_LRU_GEN_ENABLED + return static_branch_likely(&lru_gen_caps[cap]); +#else + return static_branch_unlikely(&lru_gen_caps[cap]); +#endif +} + static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid) { struct pglist_data *pgdat =3D NODE_DATA(nid); @@ -3833,7 +3849,8 @@ static void walk_pmd_range_locked(pud_t *pud, unsigne= d long next, struct vm_area goto next; =20 if (!pmd_trans_huge(pmd[i])) { - if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG)) + if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) && + get_cap(LRU_GEN_NONLEAF_YOUNG)) pmdp_test_and_clear_young(vma, addr, pmd + i); goto next; } @@ -3940,10 +3957,12 @@ static void walk_pmd_range(pud_t *pud, unsigned lon= g start, unsigned long end, priv->mm_stats[MM_PMD_TOTAL]++; =20 #ifdef CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG - if (!pmd_young(val)) - continue; + if (get_cap(LRU_GEN_NONLEAF_YOUNG)) { + if (!pmd_young(val)) + continue; =20 - walk_pmd_range_locked(pud, addr, vma, walk, &pos); + walk_pmd_range_locked(pud, addr, vma, walk, &pos); + } #endif if (!priv->full_scan && !test_bloom_filter(priv->lruvec, priv->max_seq, = pmd + i)) continue; @@ -4180,7 +4199,7 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec,= unsigned long max_seq, * handful of PTEs. Spreading the work out over a period of time usually * is less efficient, but it avoids bursty page faults. */ - if (!full_scan && !arch_has_hw_pte_young()) { + if (!full_scan && (!arch_has_hw_pte_young() || !get_cap(LRU_GEN_MM_WALK))= ) { success =3D iterate_mm_list_nowalk(lruvec, max_seq); goto done; } @@ -4910,6 +4929,211 @@ static void lru_gen_shrink_lruvec(struct lruvec *lr= uvec, struct scan_control *sc blk_finish_plug(&plug); } =20 +/*************************************************************************= ***** + * state change + *************************************************************************= *****/ + +static bool __maybe_unused state_is_valid(struct lruvec *lruvec) +{ + struct lru_gen_struct *lrugen =3D &lruvec->lrugen; + + if (lrugen->enabled) { + enum lru_list lru; + + for_each_evictable_lru(lru) { + if (!list_empty(&lruvec->lists[lru])) + return false; + } + } else { + int gen, type, zone; + + for_each_gen_type_zone(gen, type, zone) { + if (!list_empty(&lrugen->lists[gen][type][zone])) + return false; + + /* unlikely but not a bug when reset_batch_size() is pending */ + VM_WARN_ON(lrugen->nr_pages[gen][type][zone]); + } + } + + return true; +} + +static bool fill_evictable(struct lruvec *lruvec) +{ + enum lru_list lru; + int remaining =3D MAX_LRU_BATCH; + + for_each_evictable_lru(lru) { + int type =3D is_file_lru(lru); + bool active =3D is_active_lru(lru); + struct list_head *head =3D &lruvec->lists[lru]; + + while (!list_empty(head)) { + bool success; + struct folio *folio =3D lru_to_folio(head); + + VM_BUG_ON_FOLIO(folio_test_unevictable(folio), folio); + VM_BUG_ON_FOLIO(folio_test_active(folio) !=3D active, folio); + VM_BUG_ON_FOLIO(folio_is_file_lru(folio) !=3D type, folio); + VM_BUG_ON_FOLIO(folio_lru_gen(folio) < MAX_NR_GENS, folio); + + lruvec_del_folio(lruvec, folio); + success =3D lru_gen_add_folio(lruvec, folio, false); + VM_BUG_ON(!success); + + if (!--remaining) + return false; + } + } + + return true; +} + +static bool drain_evictable(struct lruvec *lruvec) +{ + int gen, type, zone; + int remaining =3D MAX_LRU_BATCH; + + for_each_gen_type_zone(gen, type, zone) { + struct list_head *head =3D &lruvec->lrugen.lists[gen][type][zone]; + + while (!list_empty(head)) { + bool success; + struct folio *folio =3D lru_to_folio(head); + + VM_BUG_ON_FOLIO(folio_test_unevictable(folio), folio); + VM_BUG_ON_FOLIO(folio_test_active(folio), folio); + VM_BUG_ON_FOLIO(folio_is_file_lru(folio) !=3D type, folio); + VM_BUG_ON_FOLIO(folio_zonenum(folio) !=3D zone, folio); + + success =3D lru_gen_del_folio(lruvec, folio, false); + VM_BUG_ON(!success); + lruvec_add_folio(lruvec, folio); + + if (!--remaining) + return false; + } + } + + return true; +} + +static void lru_gen_change_state(bool enable) +{ + static DEFINE_MUTEX(state_mutex); + + struct mem_cgroup *memcg; + + cgroup_lock(); + cpus_read_lock(); + get_online_mems(); + mutex_lock(&state_mutex); + + if (enable =3D=3D lru_gen_enabled()) + goto unlock; + + if (enable) + static_branch_enable_cpuslocked(&lru_gen_caps[LRU_GEN_CORE]); + else + static_branch_disable_cpuslocked(&lru_gen_caps[LRU_GEN_CORE]); + + memcg =3D mem_cgroup_iter(NULL, NULL, NULL); + do { + int nid; + + for_each_node(nid) { + struct lruvec *lruvec =3D get_lruvec(memcg, nid); + + if (!lruvec) + continue; + + spin_lock_irq(&lruvec->lru_lock); + + VM_BUG_ON(!seq_is_valid(lruvec)); + VM_BUG_ON(!state_is_valid(lruvec)); + + lruvec->lrugen.enabled =3D enable; + + while (!(enable ? fill_evictable(lruvec) : drain_evictable(lruvec))) { + spin_unlock_irq(&lruvec->lru_lock); + cond_resched(); + spin_lock_irq(&lruvec->lru_lock); + } + + spin_unlock_irq(&lruvec->lru_lock); + } + + cond_resched(); + } while ((memcg =3D mem_cgroup_iter(NULL, memcg, NULL))); +unlock: + mutex_unlock(&state_mutex); + put_online_mems(); + cpus_read_unlock(); + cgroup_unlock(); +} + +/*************************************************************************= ***** + * sysfs interface + *************************************************************************= *****/ + +static ssize_t show_enable(struct kobject *kobj, struct kobj_attribute *at= tr, char *buf) +{ + unsigned int caps =3D 0; + + if (get_cap(LRU_GEN_CORE)) + caps |=3D BIT(LRU_GEN_CORE); + + if (arch_has_hw_pte_young() && get_cap(LRU_GEN_MM_WALK)) + caps |=3D BIT(LRU_GEN_MM_WALK); + + if (IS_ENABLED(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) && get_cap(LRU_GEN_NONL= EAF_YOUNG)) + caps |=3D BIT(LRU_GEN_NONLEAF_YOUNG); + + return snprintf(buf, PAGE_SIZE, "0x%04x\n", caps); +} + +static ssize_t store_enable(struct kobject *kobj, struct kobj_attribute *a= ttr, + const char *buf, size_t len) +{ + int i; + unsigned int caps; + + if (tolower(*buf) =3D=3D 'n') + caps =3D 0; + else if (tolower(*buf) =3D=3D 'y') + caps =3D -1; + else if (kstrtouint(buf, 0, &caps)) + return -EINVAL; + + for (i =3D 0; i < NR_LRU_GEN_CAPS; i++) { + bool enable =3D caps & BIT(i); + + if (i =3D=3D LRU_GEN_CORE) + lru_gen_change_state(enable); + else if (enable) + static_branch_enable(&lru_gen_caps[i]); + else + static_branch_disable(&lru_gen_caps[i]); + } + + return len; +} + +static struct kobj_attribute lru_gen_enabled_attr =3D __ATTR( + enabled, 0644, show_enable, store_enable +); + +static struct attribute *lru_gen_attrs[] =3D { + &lru_gen_enabled_attr.attr, + NULL +}; + +static struct attribute_group lru_gen_attr_group =3D { + .name =3D "lru_gen", + .attrs =3D lru_gen_attrs, +}; + /*************************************************************************= ***** * initialization *************************************************************************= *****/ @@ -4920,6 +5144,7 @@ void lru_gen_init_lruvec(struct lruvec *lruvec) struct lru_gen_struct *lrugen =3D &lruvec->lrugen; =20 lrugen->max_seq =3D MIN_NR_GENS + 1; + lrugen->enabled =3D lru_gen_enabled(); =20 for_each_gen_type_zone(gen, type, zone) INIT_LIST_HEAD(&lrugen->lists[gen][type][zone]); @@ -4960,6 +5185,9 @@ static int __init init_lru_gen(void) BUILD_BUG_ON(BIT(LRU_GEN_WIDTH) <=3D MAX_NR_GENS); BUILD_BUG_ON(sizeof(MM_STAT_CODES) !=3D NR_MM_STATS + 1); =20 + if (sysfs_create_group(mm_kobj, &lru_gen_attr_group)) + pr_err("lru_gen: failed to create sysfs group\n"); + return 0; }; late_initcall(init_lru_gen); --=20 2.35.1.1094.g7c7d902a7c-goog