Re: [PATCH mm v2 6/9] memcg: enable accounting for percpu allocation of struct cgroup_rstat_cpu

Vasily Averin
2022-05-21T17:58:35Z

On 5/21/22 19:38, Vasily Averin wrote:
> struct cgroup_rstat_cpu is percpu allocated for each new cgroup and
> can consume a significant portion of all allocated memory on nodes
> with a large number of CPUs.
>
> Common part of the cgroup creation:
> Allocs Alloc $1*$2 Sum Allocation
> number size
> --------------------------------------------
> 16 ~ 352 5632 5632 KERNFS
> 1 + 4096 4096 9728 (cgroup_mkdir+0xe4)
> 1 584 584 10312 (radix_tree_node_alloc.constprop.0+0x89)
> 1 192 192 10504 (__d_alloc+0x29)
> 2 72 144 10648 (avc_alloc_node+0x27)
> 2 64 128 10776 (percpu_ref_init+0x6a)
> 1 64 64 10840 (memcg_list_lru_alloc+0x21a)
> percpu:
> 1 + 192 192 192 call_site=psi_cgroup_alloc+0x1e
> 1 + 96 96 288 call_site=cgroup_rstat_init+0x5f
> 2 12 24 312 call_site=percpu_ref_init+0x23
> 1 6 6 318 call_site=__percpu_counter_init+0x22
>
> '+' -- to be accounted,
> '~' -- partially accounted
>
> Signed-off-by: Vasily Averin <vvs-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>
> ---
> kernel/cgroup/rstat.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
> index 24b5c2ab5598..f76cb63ae2e0 100644
> --- a/kernel/cgroup/rstat.c
> +++ b/kernel/cgroup/rstat.c
> @@ -257,7 +257,8 @@ int cgroup_rstat_init(struct cgroup *cgrp)
>
> /* the root cgrp has rstat_cpu preallocated */
> if (!cgrp->rstat_cpu) {
> - cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu);
> + cgrp->rstat_cpu = alloc_percpu_gfp(struct cgroup_rstat_cpu
"," was lost here
> + GFP_KERNEL_ACCOUNT);
> if (!cgrp->rstat_cpu)
> return -ENOMEM;
> }