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Howlett" , Lorenzo Stoakes , Matthew Brost , Mel Gorman , Michal Hocko , Michal Hocko , Mike Rapoport , Muchun Song , Peter Zijlstra , Qi Zheng , Rakie Kim , Roman Gushchin , Shakeel Butt , Steven Rostedt , Suren Baghdasaryan , "T.J. Mercier" , Valentin Schneider , Vincent Guittot , Vlastimil Babka , Wei Xu , Ying Huang , Yosry Ahmed , Yuanchu Xie , Zi Yan , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-team@meta.com Subject: [RFC PATCH v3 05/14] mm/memcontrol: Set tier limits proportional to memory limits Date: Fri, 7 Aug 2026 13:20:48 -0700 Message-ID: <20260807202059.2620949-6-joshua.hahnjy@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260807202059.2620949-1-joshua.hahnjy@gmail.com> References: <20260807202059.2620949-1-joshua.hahnjy@gmail.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Compute proportional per-tier limits based on memory limits when users write to memory limit sysfs files, or when memory hotplug causes tier proportions to be shifted. No-op unless the system has tiered memcg limits enabled. Signed-off-by: Joshua Hahn --- include/linux/memcontrol.h | 10 +++++++ include/linux/memory-tiers.h | 6 ++++ mm/memcontrol.c | 54 ++++++++++++++++++++++++++++++++++++ mm/memory-tiers.c | 13 +++++++++ 4 files changed, 83 insertions(+) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index bb5bde87ac85a..f7a92b66330ec 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -537,11 +537,17 @@ static inline bool mem_cgroup_tiered_limits(void) { return static_branch_unlikely(&memcg_tiered_limits_key); } + +void establish_memcg_tier_limits(void); #else static inline bool mem_cgroup_tiered_limits(void) { return false; } + +static inline void establish_memcg_tier_limits(void) +{ +} #endif static inline void mem_cgroup_protection(struct mem_cgroup *root, @@ -1102,6 +1108,10 @@ static inline bool mem_cgroup_tiered_limits(void) return false; } +static inline void establish_memcg_tier_limits(void) +{ +} + static inline void memcg_memory_event(struct mem_cgroup *memcg, enum memcg_memory_event event) { diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h index 0e49645cdd1a9..04b396f60b457 100644 --- a/include/linux/memory-tiers.h +++ b/include/linux/memory-tiers.h @@ -55,6 +55,7 @@ struct memory_dev_type *mt_find_alloc_memory_type(int adist, struct list_head *memory_types); void mt_put_memory_types(struct list_head *memory_types); const nodemask_t *mt_tier_nodes(int slot); +unsigned long mt_scale_by_tier(unsigned long val, int slot); #ifdef CONFIG_NUMA_MIGRATION int next_demotion_node(int node, const nodemask_t *allowed_mask); void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets); @@ -169,5 +170,10 @@ static inline const nodemask_t *mt_tier_nodes(int slot) { return NULL; } + +static inline unsigned long mt_scale_by_tier(unsigned long val, int slot) +{ + return val; +} #endif /* CONFIG_NUMA */ #endif /* _LINUX_MEMORY_TIERS_H */ diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d096010366515..defd04acfb3fd 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4421,6 +4421,35 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css) mem_cgroup_free(memcg); } +static inline unsigned long page_counter_max_or_scale(unsigned long val, + int slot) +{ + return val == PAGE_COUNTER_MAX ? PAGE_COUNTER_MAX : + mt_scale_by_tier(val, slot); +} + +static void memcg_scale_tier_limits(struct mem_cgroup *memcg) +{ + unsigned long min = READ_ONCE(memcg->memory.min); + unsigned long low = READ_ONCE(memcg->memory.low); + unsigned long high = READ_ONCE(memcg->memory.high); + unsigned long max = READ_ONCE(memcg->memory.max); + int nr_tier_slots = mt_nr_tier_slots(); + + for (int slot = 0; slot < nr_tier_slots; slot++) { + unsigned long new_min = page_counter_max_or_scale(min, slot); + unsigned long new_low = page_counter_max_or_scale(low, slot); + unsigned long new_high = page_counter_max_or_scale(high, slot); + unsigned long new_max = page_counter_max_or_scale(max, slot); + struct page_counter *tier = &memcg->tier[slot]; + + page_counter_set_min(tier, new_min); + page_counter_set_low(tier, new_low); + page_counter_set_high(tier, new_high); + xchg(&tier->max, new_max); + } +} + /** * mem_cgroup_css_reset - reset the states of a mem_cgroup * @css: the target css @@ -4454,6 +4483,8 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css) page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX); memcg1_soft_limit_reset(memcg); page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX); + if (mem_cgroup_tiered_limits()) + memcg_scale_tier_limits(memcg); memcg_wb_domain_size_changed(memcg); } @@ -4797,6 +4828,21 @@ static ssize_t memory_peak_write(struct kernfs_open_file *of, char *buf, &memcg->memory_peaks); } +#ifdef CONFIG_NUMA +void establish_memcg_tier_limits(void) +{ + struct mem_cgroup *memcg; + + if (!mem_cgroup_tiered_limits()) + return; + + for_each_mem_cgroup_tree(memcg, NULL) { + if (memcg != root_mem_cgroup) + memcg_scale_tier_limits(memcg); + } +} +#endif + #undef OFP_PEAK_UNSET static int memory_min_show(struct seq_file *m, void *v) @@ -4818,6 +4864,8 @@ static ssize_t memory_min_write(struct kernfs_open_file *of, return err; page_counter_set_min(&memcg->memory, min); + if (mem_cgroup_tiered_limits()) + memcg_scale_tier_limits(memcg); return nbytes; } @@ -4841,6 +4889,8 @@ static ssize_t memory_low_write(struct kernfs_open_file *of, return err; page_counter_set_low(&memcg->memory, low); + if (mem_cgroup_tiered_limits()) + memcg_scale_tier_limits(memcg); return nbytes; } @@ -4866,6 +4916,8 @@ static ssize_t memory_high_write(struct kernfs_open_file *of, return err; page_counter_set_high(&memcg->memory, high); + if (mem_cgroup_tiered_limits()) + memcg_scale_tier_limits(memcg); if (of->file->f_flags & O_NONBLOCK) goto out; @@ -4925,6 +4977,8 @@ static ssize_t memory_max_write(struct kernfs_open_file *of, return err; xchg(&memcg->memory.max, max); + if (mem_cgroup_tiered_limits()) + memcg_scale_tier_limits(memcg); if (of->file->f_flags & O_NONBLOCK) goto out; diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c index bd5c78cd26ec4..e2c99f51c36d1 100644 --- a/mm/memory-tiers.c +++ b/mm/memory-tiers.c @@ -810,6 +810,7 @@ static int __init memory_tier_late_init(void) establish_demotion_targets(); establish_tier_slots(); + establish_memcg_tier_limits(); put_online_mems(); return 0; @@ -967,6 +968,16 @@ const nodemask_t *mt_tier_nodes(int slot) return &tier_nodemasks[slot]; } +unsigned long mt_scale_by_tier(unsigned long val, int slot) +{ + unsigned long total_capacity = totalram_pages(); + + if (slot < 0 || !total_capacity) + return 0; + + return mult_frac(val, READ_ONCE(tier_capacity[slot]), total_capacity); +} + static int __meminit memtier_hotplug_callback(struct notifier_block *self, unsigned long action, void *_arg) { @@ -979,6 +990,7 @@ static int __meminit memtier_hotplug_callback(struct notifier_block *self, if (clear_node_memory_tier(nn->nid)) { establish_demotion_targets(); establish_tier_slots(); + establish_memcg_tier_limits(); } mutex_unlock(&memory_tier_lock); break; @@ -988,6 +1000,7 @@ static int __meminit memtier_hotplug_callback(struct notifier_block *self, if (!IS_ERR(memtier)) { establish_demotion_targets(); establish_tier_slots(); + establish_memcg_tier_limits(); } mutex_unlock(&memory_tier_lock); break; -- 2.53.0-Meta