On Thu, 14 Apr 2011 15:54:28 -0700
Ying Han <yinghan@xxxxxxxxxx> wrote:
> This add the API which exports per-memcg kswapd thread pid. The kswapd
> thread is named as "memcg_" + css_id, and the pid can be used to put
> kswapd thread into cpu cgroup later.
>
> $ mkdir /dev/cgroup/memory/A
> $ cat /dev/cgroup/memory/A/memory.kswapd_pid
> memcg_null 0
>
> $ echo 500m >/dev/cgroup/memory/A/memory.limit_in_bytes
> $ echo 50m >/dev/cgroup/memory/A/memory.high_wmark_distance
> $ ps -ef | grep memcg
> root 6727 2 0 14:32 ? 00:00:00 [memcg_3]
> root 6729 6044 0 14:32 ttyS0 00:00:00 grep memcg
>
> $ cat memory.kswapd_pid
> memcg_3 6727
>
> changelog v4..v3
> 1. Add the API based on KAMAZAWA's request on patch v3.
>
> Signed-off-by: Ying Han <yinghan@xxxxxxxxxx>
Thank you.
> ---
> include/linux/swap.h | 2 ++
> mm/memcontrol.c | 33 +++++++++++++++++++++++++++++++++
> mm/vmscan.c | 2 +-
> 3 files changed, 36 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 319b800..2d3e21a 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -34,6 +34,8 @@ struct kswapd {
> };
>
> int kswapd(void *p);
> +extern spinlock_t kswapds_spinlock;
> +
> /*
> * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
> * be swapped to. The swap type and the offset into that swap type are
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 1b23ff4..606b680 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4493,6 +4493,35 @@ static int mem_cgroup_wmark_read(struct cgroup *cgrp,
> return 0;
> }
>
> +static int mem_cgroup_kswapd_pid_read(struct cgroup *cgrp,
> + struct cftype *cft, struct cgroup_map_cb *cb)
> +{
> + struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
> + struct task_struct *kswapd_thr = NULL;
> + struct kswapd *kswapd_p = NULL;
> + wait_queue_head_t *wait;
> + char name[TASK_COMM_LEN];
> + pid_t pid = 0;
> +
I think '0' is ... not very good. This '0' implies there is no kswapd.
But 0 is root pid. I have no idea. Do you have no concern ?
Otherewise, the interface seems good.
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> + sprintf(name, "memcg_null");
> +
> + spin_lock(&kswapds_spinlock);
> + wait = mem_cgroup_kswapd_wait(mem);
> + if (wait) {
> + kswapd_p = container_of(wait, struct kswapd, kswapd_wait);
> + kswapd_thr = kswapd_p->kswapd_task;
> + if (kswapd_thr) {
> + get_task_comm(name, kswapd_thr);
> + pid = kswapd_thr->pid;
> + }
> + }
> + spin_unlock(&kswapds_spinlock);
> +
> + cb->fill(cb, name, pid);
> +
> + return 0;
> +}
> +
> static int mem_cgroup_oom_control_read(struct cgroup *cgrp,
> struct cftype *cft, struct cgroup_map_cb *cb)
> {
> @@ -4610,6 +4639,10 @@ static struct cftype mem_cgroup_files[] = {
> .name = "reclaim_wmarks",
> .read_map = mem_cgroup_wmark_read,
> },
> + {
> + .name = "kswapd_pid",
> + .read_map = mem_cgroup_kswapd_pid_read,
> + },
> };
>
> #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index c081112..df4e5dd 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2249,7 +2249,7 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
> return balanced_pages > (present_pages >> 2);
> }
>
> -static DEFINE_SPINLOCK(kswapds_spinlock);
> +DEFINE_SPINLOCK(kswapds_spinlock);
> #define is_node_kswapd(kswapd_p) (!(kswapd_p)->kswapd_mem)
>
> /* is kswapd sleeping prematurely? */
> --
> 1.7.3.1
>
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