From: "Huang, Ying" <ying.huang@intel.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org,
Wei Xu <weixugc@google.com>, Yang Shi <shy828301@gmail.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Tim C Chen <tim.c.chen@intel.com>,
Michal Hocko <mhocko@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Hesham Almatary <hesham.almatary@huawei.com>,
Dave Hansen <dave.hansen@intel.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Alistair Popple <apopple@nvidia.com>,
Dan Williams <dan.j.williams@intel.com>,
Johannes Weiner <hannes@cmpxchg.org>,
jvgediya.oss@gmail.com
Subject: Re: [PATCH v10 6/8] mm/demotion: Add pg_data_t member to track node memory tier details
Date: Tue, 26 Jul 2022 16:02:33 +0800 [thread overview]
Message-ID: <87wnc0uwrq.fsf@yhuang6-desk2.ccr.corp.intel.com> (raw)
In-Reply-To: <20220720025920.1373558-7-aneesh.kumar@linux.ibm.com> (Aneesh Kumar K. V.'s message of "Wed, 20 Jul 2022 08:29:18 +0530")
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes:
> Also update different helpes to use NODE_DATA()->memtier. Since
> node specific memtier can change based on the reassignment of
> NUMA node to a different memory tiers, accessing NODE_DATA()->memtier
> needs to happen under an rcu read lock or memory_tier_lock.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> ---
> include/linux/mmzone.h | 3 ++
> mm/memory-tiers.c | 65 +++++++++++++++++++++++++++++++++++-------
> 2 files changed, 57 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index aab70355d64f..353812495a70 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -928,6 +928,9 @@ typedef struct pglist_data {
> /* Per-node vmstats */
> struct per_cpu_nodestat __percpu *per_cpu_nodestats;
> atomic_long_t vm_stat[NR_VM_NODE_STAT_ITEMS];
> +#ifdef CONFIG_NUMA
> + struct memory_tier __rcu *memtier;
> +#endif
> } pg_data_t;
>
> #define node_present_pages(nid) (NODE_DATA(nid)->node_present_pages)
> diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
> index a8cfe2ca3903..4715f9b96a44 100644
> --- a/mm/memory-tiers.c
> +++ b/mm/memory-tiers.c
> @@ -138,13 +138,18 @@ static struct memory_tier *find_create_memory_tier(unsigned int perf_level)
>
> static struct memory_tier *__node_get_memory_tier(int node)
> {
> - struct memory_tier *memtier;
> + pg_data_t *pgdat;
>
> - list_for_each_entry(memtier, &memory_tiers, list) {
> - if (node_isset(node, memtier->nodelist))
> - return memtier;
> - }
> - return NULL;
> + pgdat = NODE_DATA(node);
> + if (!pgdat)
> + return NULL;
> + /*
> + * Since we hold memory_tier_lock, we can avoid
> + * RCU read locks when accessing the details. No
> + * parallel updates are possible here.
> + */
> + return rcu_dereference_check(pgdat->memtier,
> + lockdep_is_held(&memory_tier_lock));
> }
>
> #ifdef CONFIG_MIGRATION
> @@ -277,6 +282,29 @@ static inline void disable_all_migrate_targets(void) {}
> static inline void establish_migration_targets(void) {}
> #endif /* CONFIG_MIGRATION */
>
> +static void memtier_node_set(int node, struct memory_tier *memtier)
> +{
> + pg_data_t *pgdat;
> + struct memory_tier *current_memtier;
> +
> + pgdat = NODE_DATA(node);
> + if (!pgdat)
> + return;
> + /*
> + * Make sure we mark the memtier NULL before we assign the new memory tier
> + * to the NUMA node. This make sure that anybody looking at NODE_DATA
> + * finds a NULL memtier or the one which is still valid.
> + */
> + current_memtier = rcu_dereference_check(pgdat->memtier,
> + lockdep_is_held(&memory_tier_lock));
> + rcu_assign_pointer(pgdat->memtier, NULL);
> + synchronize_rcu();
> + if (current_memtier)
> + node_clear(node, current_memtier->nodelist);
If pgdat->memtier == NULL, we don't need to set it to NULL and call
synchronize_rcu(). That is,
+ current_memtier = rcu_dereference_check(pgdat->memtier,
+ lockdep_is_held(&memory_tier_lock));
+ if (current_memtier) {
+ rcu_assign_pointer(pgdat->memtier, NULL);
+ synchronize_rcu();
+ node_clear(node, current_memtier->nodelist);
+ }
Same for clear_node_memory_tier().
Best Regards,
Huang, Ying
> + node_set(node, memtier->nodelist);
> + rcu_assign_pointer(pgdat->memtier, memtier);
> +}
> +
> static void init_node_memory_tier(int node)
> {
> int perf_level;
> @@ -295,7 +323,7 @@ static void init_node_memory_tier(int node)
> if (!memtier) {
> perf_level = node_devices[node]->perf_level;
> memtier = find_create_memory_tier(perf_level);
> - node_set(node, memtier->nodelist);
> + memtier_node_set(node, memtier);
> }
> establish_migration_targets();
> mutex_unlock(&memory_tier_lock);
> @@ -303,12 +331,25 @@ static void init_node_memory_tier(int node)
>
> static void clear_node_memory_tier(int node)
> {
> - struct memory_tier *memtier;
> + pg_data_t *pgdat;
> + struct memory_tier *current_memtier;
> +
> + pgdat = NODE_DATA(node);
> + if (!pgdat)
> + return;
>
> mutex_lock(&memory_tier_lock);
> - memtier = __node_get_memory_tier(node);
> - if (memtier) {
> - node_clear(node, memtier->nodelist);
> + /*
> + * Make sure we mark the memtier NULL before we assign the new memory tier
> + * to the NUMA node. This make sure that anybody looking at NODE_DATA
> + * finds a NULL memtier or the one which is still valid.
> + */
> + current_memtier = rcu_dereference_check(pgdat->memtier,
> + lockdep_is_held(&memory_tier_lock));
> + rcu_assign_pointer(pgdat->memtier, NULL);
> + synchronize_rcu();
> + if (current_memtier) {
> + node_clear(node, current_memtier->nodelist);
> establish_migration_targets();
> }
> mutex_unlock(&memory_tier_lock);
> @@ -383,6 +424,8 @@ static int __init memory_tier_init(void)
>
> if (!node_property->perf_level)
> node_property->perf_level = default_memtier_perf_level;
> +
> + rcu_assign_pointer(NODE_DATA(node)->memtier, memtier);
> }
> mutex_unlock(&memory_tier_lock);
next prev parent reply other threads:[~2022-07-26 8:02 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-20 2:59 [PATCH v10 0/8] mm/demotion: Memory tiers and demotion Aneesh Kumar K.V
2022-07-20 2:59 ` [PATCH v10 1/8] mm/demotion: Add support for explicit memory tiers Aneesh Kumar K.V
2022-07-26 3:53 ` Huang, Ying
2022-07-26 11:59 ` Aneesh Kumar K V
2022-07-27 1:16 ` Huang, Ying
2022-07-28 17:23 ` Johannes Weiner
2022-07-20 2:59 ` [PATCH v10 2/8] mm/demotion: Move memory demotion related code Aneesh Kumar K.V
2022-07-20 2:59 ` [PATCH v10 3/8] mm/demotion: Add hotplug callbacks to handle new numa node onlined Aneesh Kumar K.V
2022-07-26 4:03 ` Huang, Ying
2022-07-26 12:03 ` Aneesh Kumar K V
2022-07-27 1:53 ` Huang, Ying
2022-07-27 4:38 ` Aneesh Kumar K.V
2022-07-28 6:42 ` Huang, Ying
2022-07-20 2:59 ` [PATCH v10 4/8] mm/demotion/dax/kmem: Set node's performance level to MEMTIER_PERF_LEVEL_PMEM Aneesh Kumar K.V
2022-07-21 6:07 ` kernel test robot
2022-07-25 6:37 ` Huang, Ying
2022-07-25 6:48 ` Aneesh Kumar K V
2022-07-25 8:35 ` Huang, Ying
2022-07-25 8:42 ` Aneesh Kumar K V
2022-07-26 2:13 ` Huang, Ying
2022-07-27 4:31 ` Aneesh Kumar K.V
2022-07-28 6:39 ` Huang, Ying
2022-07-20 2:59 ` [PATCH v10 5/8] mm/demotion: Build demotion targets based on explicit memory tiers Aneesh Kumar K.V
2022-07-20 3:38 ` Aneesh Kumar K.V
2022-07-21 0:02 ` kernel test robot
2022-07-26 7:44 ` Huang, Ying
2022-07-26 12:30 ` Aneesh Kumar K V
2022-07-27 1:40 ` Huang, Ying
2022-07-27 4:35 ` Aneesh Kumar K.V
2022-07-28 6:51 ` Huang, Ying
2022-08-03 3:18 ` Aneesh Kumar K.V
2022-08-04 4:19 ` Huang, Ying
2022-07-20 2:59 ` [PATCH v10 6/8] mm/demotion: Add pg_data_t member to track node memory tier details Aneesh Kumar K.V
2022-07-26 8:02 ` Huang, Ying [this message]
2022-07-20 2:59 ` [PATCH v10 7/8] mm/demotion: Demote pages according to allocation fallback order Aneesh Kumar K.V
2022-07-26 8:24 ` Huang, Ying
2022-07-20 2:59 ` [PATCH v10 8/8] mm/demotion: Update node_is_toptier to work with memory tiers Aneesh Kumar K.V
2022-07-25 8:54 ` Huang, Ying
2022-07-25 8:56 ` Aneesh Kumar K V
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