| Message ID | 20231010000929.450702-4-roman.gushchin@linux.dev (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: improve performance of accounted kernel memory allocations | expand |
On Mon, Oct 09, 2023 at 05:09:27PM -0700, Roman Gushchin wrote: > Keep a reference to the original objcg object for the entire life > of a memcg structure. > > This allows to simplify the synchronization on the kernel memory > allocation paths: pinning a (live) memcg will also pin the > corresponding objcg. > > The memory overhead of this change is minimal because object cgroups > usually outlive their corresponding memory cgroups even without this > change, so it's only an additional pointer per memcg. > > Signed-off-by: Roman Gushchin (Cruise) <roman.gushchin@linux.dev> Acked-by: Shakeel Butt <shakeelb@google.com>
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index ab94ad4597d0..277690af383d 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -299,7 +299,13 @@ struct mem_cgroup { #ifdef CONFIG_MEMCG_KMEM int kmemcg_id; - struct obj_cgroup __rcu *objcg; + /* + * memcg->objcg is wiped out as a part of the objcg repaprenting + * process. memcg->orig_objcg preserves a pointer (and a reference) + * to the original objcg until the end of live of memcg. + */ + struct obj_cgroup __rcu *objcg; + struct obj_cgroup *orig_objcg; /* list of inherited objcgs, protected by objcg_lock */ struct list_head objcg_list; #endif diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a2efeea43058..490c5f67be79 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3808,6 +3808,8 @@ static int memcg_online_kmem(struct mem_cgroup *memcg) objcg->memcg = memcg; rcu_assign_pointer(memcg->objcg, objcg); + obj_cgroup_get(objcg); + memcg->orig_objcg = objcg; static_branch_enable(&memcg_kmem_online_key); @@ -5302,6 +5304,9 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg) { int node; + if (memcg->orig_objcg) + obj_cgroup_put(memcg->orig_objcg); + for_each_node(node) free_mem_cgroup_per_node_info(memcg, node); kfree(memcg->vmstats);
Keep a reference to the original objcg object for the entire life of a memcg structure. This allows to simplify the synchronization on the kernel memory allocation paths: pinning a (live) memcg will also pin the corresponding objcg. The memory overhead of this change is minimal because object cgroups usually outlive their corresponding memory cgroups even without this change, so it's only an additional pointer per memcg. Signed-off-by: Roman Gushchin (Cruise) <roman.gushchin@linux.dev> --- include/linux/memcontrol.h | 8 +++++++- mm/memcontrol.c | 5 +++++ 2 files changed, 12 insertions(+), 1 deletion(-)