> Add the kswapd_mem field in kswapd descriptor which links the kswapd
> kernel thread to a memcg. The per-memcg kswapd is sleeping in the wait
> queue headed at kswapd_wait field of the kswapd descriptor.
>
> The kswapd() function is now shared between global and per-memcg kswapd. It
> is passed in with the kswapd descriptor which contains the information of
> either node or memcg. Then the new function balance_mem_cgroup_pgdat is
> invoked if it is per-mem kswapd thread, and the implementation of the function
> is on the following patch.
>
> change v7..v6:
> 1. change the threading model of memcg from per-memcg-per-thread to thread-pool.
> this is based on the patch from KAMAZAWA.
>
> change v6..v5:
> 1. rename is_node_kswapd to is_global_kswapd to match the scanning_global_lru.
> 2. revert the sleeping_prematurely change, but keep the kswapd_try_to_sleep()
> for memcg.
>
> changelog v4..v3:
> 1. fix up the kswapd_run and kswapd_stop for online_pages() and offline_pages.
> 2. drop the PF_MEMALLOC flag for memcg kswapd for now per KAMAZAWA's request.
>
> changelog v3..v2:
> 1. split off from the initial patch which includes all changes of the following
> three patches.
>
> Signed-off-by: Ying Han <yinghan@xxxxxxxxxx>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Looks ok. but this one have some ugly coding style.
functioon()
{
if (is_global_kswapd()) {
looooooooong lines
...
..
} else {
another looooooong lines
...
..
}
}
please pay attention more to keep simpler code.
However, I don't think this patch has major issue. I expect I can ack next version.
> ---
> include/linux/swap.h | 2 +-
> mm/memory_hotplug.c | 2 +-
> mm/vmscan.c | 156 +++++++++++++++++++++++++++++++-------------------
> 3 files changed, 100 insertions(+), 60 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 9b91ca4..a062f0b 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -303,7 +303,7 @@ static inline void scan_unevictable_unregister_node(struct node *node)
> }
> #endif
>
> -extern int kswapd_run(int nid);
> +extern int kswapd_run(int nid, int id);
"id" is bad name. there is no information. please use memcg-id or so on.
> extern void kswapd_stop(int nid);
>
> #ifdef CONFIG_MMU
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 321fc74..36b4eed 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -462,7 +462,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
> setup_per_zone_wmarks();
> calculate_zone_inactive_ratio(zone);
> if (onlined_pages) {
> - kswapd_run(zone_to_nid(zone));
> + kswapd_run(zone_to_nid(zone), 0);
> node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
> }
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 7aba681..63c557e 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2241,6 +2241,8 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
> return balanced_pages > (present_pages >> 2);
> }
>
> +#define is_global_kswapd(kswapd_p) ((kswapd_p)->kswapd_pgdat)
please use inline function.
> +
> /* is kswapd sleeping prematurely? */
> static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining,
> int classzone_idx)
> @@ -2583,40 +2585,46 @@ static void kswapd_try_to_sleep(struct kswapd *kswapd_p, int order,
>
> prepare_to_wait(wait_h, &wait, TASK_INTERRUPTIBLE);
>
> - /* Try to sleep for a short interval */
> - if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
> - remaining = schedule_timeout(HZ/10);
> - finish_wait(wait_h, &wait);
> - prepare_to_wait(wait_h, &wait, TASK_INTERRUPTIBLE);
> - }
> -
> - /*
> - * After a short sleep, check if it was a premature sleep. If not, then
> - * go fully to sleep until explicitly woken up.
> - */
> - if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) {
> - trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
> + if (is_global_kswapd(kswapd_p)) {
bad indentation. :-/
please don't increase coding mess.
if (!is_global_kswapd(kswapd_p)) {
kswapd_try_to_sleep_memcg();
return;
}
is simpler.
> + /* Try to sleep for a short interval */
> + if (!sleeping_prematurely(pgdat, order,
> + remaining, classzone_idx)) {
> + remaining = schedule_timeout(HZ/10);
> + finish_wait(wait_h, &wait);
> + prepare_to_wait(wait_h, &wait, TASK_INTERRUPTIBLE);
> + }
>
> /*
> - * vmstat counters are not perfectly accurate and the estimated
> - * value for counters such as NR_FREE_PAGES can deviate from the
> - * true value by nr_online_cpus * threshold. To avoid the zone
> - * watermarks being breached while under pressure, we reduce the
> - * per-cpu vmstat threshold while kswapd is awake and restore
> - * them before going back to sleep.
> + * After a short sleep, check if it was a premature sleep.
> + * If not, then go fully to sleep until explicitly woken up.
> */
> - set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
> - schedule();
> - set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
> + if (!sleeping_prematurely(pgdat, order,
> + remaining, classzone_idx)) {
> + trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
> + set_pgdat_percpu_threshold(pgdat,
> + calculate_normal_threshold);
> + schedule();
> + set_pgdat_percpu_threshold(pgdat,
> + calculate_pressure_threshold);
> + } else {
> + if (remaining)
> + count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
> + else
> + count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
> + }
> } else {
> - if (remaining)
> - count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
> - else
> - count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
> + /* For now, we just check the remaining works.*/
> + if (mem_cgroup_kswapd_can_sleep())
> + schedule();
> }
> finish_wait(wait_h, &wait);
> }
>
> +static unsigned long shrink_mem_cgroup(struct mem_cgroup *mem_cont, int order)
> +{
> + return 0;
> +}
> +
> /*
> * The background pageout daemon, started as a kernel thread
> * from the init process.
> @@ -2636,6 +2644,7 @@ int kswapd(void *p)
> int classzone_idx;
> struct kswapd *kswapd_p = (struct kswapd *)p;
> pg_data_t *pgdat = kswapd_p->kswapd_pgdat;
> + struct mem_cgroup *mem;
> struct task_struct *tsk = current;
>
> struct reclaim_state reclaim_state = {
> @@ -2645,9 +2654,11 @@ int kswapd(void *p)
>
> lockdep_set_current_reclaim_state(GFP_KERNEL);
>
> - cpumask = cpumask_of_node(pgdat->node_id);
> - if (!cpumask_empty(cpumask))
> - set_cpus_allowed_ptr(tsk, cpumask);
> + if (is_global_kswapd(kswapd_p)) {
> + cpumask = cpumask_of_node(pgdat->node_id);
> + if (!cpumask_empty(cpumask))
> + set_cpus_allowed_ptr(tsk, cpumask);
> + }
> current->reclaim_state = &reclaim_state;
>
> /*
> @@ -2662,7 +2673,10 @@ int kswapd(void *p)
> * us from recursively trying to free more memory as we're
> * trying to free the first piece of memory in the first place).
> */
> - tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
> + if (is_global_kswapd(kswapd_p))
> + tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
> + else
> + tsk->flags |= PF_SWAPWRITE | PF_KSWAPD;
> set_freezable();
>
> order = 0;
> @@ -2672,36 +2686,48 @@ int kswapd(void *p)
> int new_classzone_idx;
> int ret;
>
> - new_order = pgdat->kswapd_max_order;
> - new_classzone_idx = pgdat->classzone_idx;
> - pgdat->kswapd_max_order = 0;
> - pgdat->classzone_idx = MAX_NR_ZONES - 1;
> - if (order < new_order || classzone_idx > new_classzone_idx) {
> - /*
> - * Don't sleep if someone wants a larger 'order'
> - * allocation or has tigher zone constraints
> - */
> - order = new_order;
> - classzone_idx = new_classzone_idx;
> - } else {
> - kswapd_try_to_sleep(kswapd_p, order, classzone_idx);
> - order = pgdat->kswapd_max_order;
> - classzone_idx = pgdat->classzone_idx;
> + if (is_global_kswapd(kswapd_p)) {
> + new_order = pgdat->kswapd_max_order;
> + new_classzone_idx = pgdat->classzone_idx;
> pgdat->kswapd_max_order = 0;
> pgdat->classzone_idx = MAX_NR_ZONES - 1;
> - }
> + if (order < new_order ||
> + classzone_idx > new_classzone_idx) {
> + /*
> + * Don't sleep if someone wants a larger 'order'
> + * allocation or has tigher zone constraints
> + */
> + order = new_order;
> + classzone_idx = new_classzone_idx;
> + } else {
> + kswapd_try_to_sleep(kswapd_p, order,
> + classzone_idx);
> + order = pgdat->kswapd_max_order;
> + classzone_idx = pgdat->classzone_idx;
> + pgdat->kswapd_max_order = 0;
> + pgdat->classzone_idx = MAX_NR_ZONES - 1;
-ETOODEEPNEST.
> + }
> + } else
> + kswapd_try_to_sleep(kswapd_p, order, classzone_idx);
>
> ret = try_to_freeze();
> if (kthread_should_stop())
> break;
>
> + if (ret)
> + continue;
> /*
> * We can speed up thawing tasks if we don't call balance_pgdat
> * after returning from the refrigerator
> */
> - if (!ret) {
> + if (is_global_kswapd(kswapd_p)) {
> trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
> order = balance_pgdat(pgdat, order, &classzone_idx);
> + } else {
> + mem = mem_cgroup_get_shrink_target();
> + if (mem)
> + shrink_mem_cgroup(mem, order);
> + mem_cgroup_put_shrink_target(mem);
> }
> }
> return 0;
> @@ -2845,30 +2871,44 @@ static int __devinit cpu_callback(struct notifier_block *nfb,
> * This kswapd start function will be called by init and node-hot-add.
> * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
> */
> -int kswapd_run(int nid)
> +int kswapd_run(int nid, int memcgid)
> {
> - pg_data_t *pgdat = NODE_DATA(nid);
> struct task_struct *kswapd_tsk;
> + pg_data_t *pgdat = NULL;
> struct kswapd *kswapd_p;
> + static char name[TASK_COMM_LEN];
> int ret = 0;
>
> - if (pgdat->kswapd)
> - return 0;
> + if (!memcgid) {
> + pgdat = NODE_DATA(nid);
> + if (pgdat->kswapd)
> + return ret;
> + }
>
> kswapd_p = kzalloc(sizeof(struct kswapd), GFP_KERNEL);
> if (!kswapd_p)
> return -ENOMEM;
>
> - pgdat->kswapd = kswapd_p;
> - kswapd_p->kswapd_wait = &pgdat->kswapd_wait;
> - kswapd_p->kswapd_pgdat = pgdat;
> + if (!memcgid) {
> + pgdat->kswapd = kswapd_p;
> + kswapd_p->kswapd_wait = &pgdat->kswapd_wait;
> + kswapd_p->kswapd_pgdat = pgdat;
> + snprintf(name, TASK_COMM_LEN, "kswapd_%d", nid);
> + } else {
> + kswapd_p->kswapd_wait = mem_cgroup_kswapd_waitq();
> + snprintf(name, TASK_COMM_LEN, "memcg_%d", memcgid);
> + }
>
> - kswapd_tsk = kthread_run(kswapd, kswapd_p, "kswapd%d", nid);
You seems to change kswapd name slightly.
> + kswapd_tsk = kthread_run(kswapd, kswapd_p, name);
> if (IS_ERR(kswapd_tsk)) {
> /* failure at boot is fatal */
> BUG_ON(system_state == SYSTEM_BOOTING);
> - printk("Failed to start kswapd on node %d\n",nid);
> - pgdat->kswapd = NULL;
> + if (!memcgid) {
> + printk(KERN_ERR "Failed to start kswapd on node %d\n",
> + nid);
> + pgdat->kswapd = NULL;
> + } else
> + printk(KERN_ERR "Failed to start kswapd on memcg\n");
Why don't you show memcg-id here?
> kfree(kswapd_p);
> ret = -1;
> } else
> @@ -2899,7 +2939,7 @@ static int __init kswapd_init(void)
>
> swap_setup();
> for_each_node_state(nid, N_HIGH_MEMORY)
> - kswapd_run(nid);
> + kswapd_run(nid, 0);
> hotcpu_notifier(cpu_callback, 0);
> return 0;
> }
> --
> 1.7.3.1
>
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