Re: [PATCH -mmotm 1/2] memcg: dirty pages accounting and limitinginfrastructure

From: Andrea Righi
Date: Mon Mar 01 2010 - 05:24:28 EST

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In reply to: Andrea Righi: "Re: [PATCH -mmotm 1/2] memcg: dirty pages accounting and limitinginfrastructure"
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On Mon, Mar 01, 2010 at 10:09:10AM +0900, KAMEZAWA Hiroyuki wrote:
> > +static unsigned long get_dirty_param(struct mem_cgroup *memcg,
> > + enum mem_cgroup_dirty_param idx)
> > +{
> > + unsigned long ret;
> > +
> > + spin_lock(&memcg->reclaim_param_lock);
>
> do we need lock ?

I think yes. Not for a single param, but when we change dirty_ratio we
need to disable dirty_bytes (set ot 0) atomically, and vice versa.

The same for dirty_background_ratio/dirty_background_bytes.

>
>
> > + switch (idx) {
> > + case MEM_CGROUP_DIRTY_RATIO:
> > + ret = memcg->dirty_ratio;
> > + break;
> > + case MEM_CGROUP_DIRTY_BYTES:
> > + ret = memcg->dirty_bytes;
> > + break;
> > + case MEM_CGROUP_DIRTY_BACKGROUND_RATIO:
> > + ret = memcg->dirty_background_ratio;
> > + break;
> > + case MEM_CGROUP_DIRTY_BACKGROUND_BYTES:
> > + ret = memcg->dirty_background_bytes;
> > + break;
> > + default:
> > + VM_BUG_ON(1);
> > + }
> > + spin_unlock(&memcg->reclaim_param_lock);
> > +
> > + return ret;
> > +}
> > +
> > +long mem_cgroup_dirty_ratio(void)
> > +{
> > + struct mem_cgroup *memcg;
> > + long ret = vm_dirty_ratio;
> > +
> > + if (mem_cgroup_disabled())
> > + goto out;
> > + rcu_read_lock();
> > + memcg = mem_cgroup_from_task(current);
>
> please add some excuse comment here. As...
>
> /*
> * It's possible that "current" may be moved to other cgroup while
> * we access cgroup. But precise check is meaningless because the task
> * can be moved after our access and writeback tends to take long time.
> * At least, "memcg" will not be freed under rcu_read_lock().
> */

OK.

>
>
> > + if (likely(memcg))
> > + ret = get_dirty_param(memcg, MEM_CGROUP_DIRTY_RATIO);
> > + rcu_read_unlock();
> > +out:
> > + return ret;
> > +}
> > +
> > +unsigned long mem_cgroup_dirty_bytes(void)
> > +{
> > + struct mem_cgroup *memcg;
> > + unsigned long ret = vm_dirty_bytes;
> > +
> > + if (mem_cgroup_disabled())
> > + goto out;
> > + rcu_read_lock();
> > + memcg = mem_cgroup_from_task(current);
> > + if (likely(memcg))
> > + ret = get_dirty_param(memcg, MEM_CGROUP_DIRTY_BYTES);
> > + rcu_read_unlock();
> > +out:
> > + return ret;
> > +}
> > +
> > +long mem_cgroup_dirty_background_ratio(void)
> > +{
> > + struct mem_cgroup *memcg;
> > + long ret = dirty_background_ratio;
> > +
> > + if (mem_cgroup_disabled())
> > + goto out;
> > + rcu_read_lock();
> > + memcg = mem_cgroup_from_task(current);
> > + if (likely(memcg))
> > + ret = get_dirty_param(memcg, MEM_CGROUP_DIRTY_BACKGROUND_RATIO);
> > + rcu_read_unlock();
> > +out:
> > + return ret;
> > +}
> > +
> > +unsigned long mem_cgroup_dirty_background_bytes(void)
> > +{
> > + struct mem_cgroup *memcg;
> > + unsigned long ret = dirty_background_bytes;
> > +
> > + if (mem_cgroup_disabled())
> > + goto out;
> > + rcu_read_lock();
> > + memcg = mem_cgroup_from_task(current);
> > + if (likely(memcg))
> > + ret = get_dirty_param(memcg, MEM_CGROUP_DIRTY_BACKGROUND_BYTES);
> > + rcu_read_unlock();
> > +out:
> > + return ret;
> > +}
> > +
> Hmm, how about
>
> memcg->dirty_params[XXXX]
> and access by memcg->dirt_params[MEM_CGROUP_DIRTY_BACKGROUND_BYTES]] ?
>
> Then, we don't need to have 4 functsion in the same implementation.

Agreed. I like this.

>
>
> > +static s64 mem_cgroup_get_local_page_stat(struct mem_cgroup *memcg,
> > + enum mem_cgroup_page_stat_item item)
> > +{
> > + s64 ret;
> > +
> > + switch (item) {
> > + case MEMCG_NR_DIRTYABLE_PAGES:
> > + ret = res_counter_read_u64(&memcg->res, RES_LIMIT) -
> > + res_counter_read_u64(&memcg->res, RES_USAGE);
> > + /* Translate free memory in pages */
> > + ret >>= PAGE_SHIFT;
> > + ret += mem_cgroup_read_stat(memcg, LRU_ACTIVE_ANON) +
> > + mem_cgroup_read_stat(memcg, LRU_ACTIVE_FILE) +
> > + mem_cgroup_read_stat(memcg, LRU_INACTIVE_ANON) +
> > + mem_cgroup_read_stat(memcg, LRU_INACTIVE_FILE);
> > + break;
> Hmm, is this correct in swapless case ?

Something like this should be better:

static inline bool mem_cgroup_can_swap(struct mem_cgroup *memcg)
{
return do_swap_account ?
res_counter_read_u64(&memcg->memsw, RES_LIMIT) :
nr_swap_pages > 0;
}
...
ret += mem_cgroup_read_stat(memcg, LRU_ACTIVE_FILE) +
mem_cgroup_read_stat(memcg, LRU_INACTIVE_FILE);
if (mem_cgroup_can_swap(memcg))
ret += mem_cgroup_read_stat(memcg, LRU_ACTIVE_ANON) +
mem_cgroup_read_stat(memcg, LRU_INACTIVE_ANON);

>
>
> > + case MEMCG_NR_RECLAIM_PAGES:
> > + ret = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_FILE_DIRTY) +
> > + mem_cgroup_read_stat(memcg,
> > + MEM_CGROUP_STAT_UNSTABLE_NFS);
> > + break;
> > + case MEMCG_NR_WRITEBACK:
> > + ret = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_WRITEBACK);
> > + break;
> > + case MEMCG_NR_DIRTY_WRITEBACK_PAGES:
> > + ret = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_WRITEBACK) +
> > + mem_cgroup_read_stat(memcg,
> > + MEM_CGROUP_STAT_UNSTABLE_NFS);
> > + break;
> > + default:
> > + ret = 0;
> > + WARN_ON_ONCE(1);
> > + }
> > + return ret;
> > +}
> > +
> > +static int mem_cgroup_page_stat_cb(struct mem_cgroup *mem, void *data)
> > +{
> > + struct mem_cgroup_page_stat *stat = (struct mem_cgroup_page_stat *)data;
> > +
> > + stat->value += mem_cgroup_get_local_page_stat(mem, stat->item);
> > + return 0;
> > +}
> > +
> > +s64 mem_cgroup_page_stat(enum mem_cgroup_page_stat_item item)
> > +{
> > + struct mem_cgroup_page_stat stat = {};
> > + struct mem_cgroup *memcg;
> > +
> > + rcu_read_lock();
> > + memcg = mem_cgroup_from_task(current);
> > + if (memcg) {
> > + /*
> > + * Recursively evaulate page statistics against all cgroup
> > + * under hierarchy tree
> > + */
> > + stat.item = item;
> > + mem_cgroup_walk_tree(memcg, &stat, mem_cgroup_page_stat_cb);
> > + } else
> > + stat.value = -ENOMEM;
> > + rcu_read_unlock();
> > +
> > + return stat.value;
> > +}
> > +
> > static int mem_cgroup_count_children_cb(struct mem_cgroup *mem, void *data)
> > {
> > int *val = data;
> > @@ -1263,10 +1419,10 @@ static void record_last_oom(struct mem_cgroup *mem)
> > }
> >
> > /*
> > - * Currently used to update mapped file statistics, but the routine can be
> > - * generalized to update other statistics as well.
> > + * Generalized routine to update memory cgroup statistics.
> > */
> > -void mem_cgroup_update_file_mapped(struct page *page, int val)
> > +void mem_cgroup_update_stat(struct page *page,
> > + enum mem_cgroup_stat_index idx, int val)
> > {
> > struct mem_cgroup *mem;
> > struct page_cgroup *pc;
> > @@ -1286,7 +1442,8 @@ void mem_cgroup_update_file_mapped(struct page *page, int val)
> > /*
> > * Preemption is already disabled. We can use __this_cpu_xxx
> > */
> > - __this_cpu_add(mem->stat->count[MEM_CGROUP_STAT_FILE_MAPPED], val);
> > + VM_BUG_ON(idx >= MEM_CGROUP_STAT_NSTATS);
> > + __this_cpu_add(mem->stat->count[idx], val);
> >
> > done:
> > unlock_page_cgroup(pc);
> > @@ -3033,6 +3190,10 @@ enum {
> > MCS_PGPGIN,
> > MCS_PGPGOUT,
> > MCS_SWAP,
> > + MCS_FILE_DIRTY,
> > + MCS_WRITEBACK,
> > + MCS_WRITEBACK_TEMP,
> > + MCS_UNSTABLE_NFS,
> > MCS_INACTIVE_ANON,
> > MCS_ACTIVE_ANON,
> > MCS_INACTIVE_FILE,
> > @@ -3055,6 +3216,10 @@ struct {
> > {"pgpgin", "total_pgpgin"},
> > {"pgpgout", "total_pgpgout"},
> > {"swap", "total_swap"},
> > + {"filedirty", "dirty_pages"},
> > + {"writeback", "writeback_pages"},
> > + {"writeback_tmp", "writeback_temp_pages"},
> > + {"nfs", "nfs_unstable"},
> > {"inactive_anon", "total_inactive_anon"},
> > {"active_anon", "total_active_anon"},
> > {"inactive_file", "total_inactive_file"},
> > @@ -3083,6 +3248,14 @@ static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data)
> > val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_SWAPOUT);
> > s->stat[MCS_SWAP] += val * PAGE_SIZE;
> > }
> > + val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_DIRTY);
> > + s->stat[MCS_FILE_DIRTY] += val;
> > + val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_WRITEBACK);
> > + s->stat[MCS_WRITEBACK] += val;
> > + val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_WRITEBACK_TEMP);
> > + s->stat[MCS_WRITEBACK_TEMP] += val;
> > + val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_UNSTABLE_NFS);
> > + s->stat[MCS_UNSTABLE_NFS] += val;
> >
> > /* per zone stat */
> > val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_ANON);
> > @@ -3467,6 +3640,100 @@ unlock:
> > return ret;
> > }
> >
> > +static u64 mem_cgroup_dirty_ratio_read(struct cgroup *cgrp, struct cftype *cft)
> > +{
> > + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > +
> > + return get_dirty_param(memcg, MEM_CGROUP_DIRTY_RATIO);
> > +}
> > +
> > +static int
> > +mem_cgroup_dirty_ratio_write(struct cgroup *cgrp, struct cftype *cft, u64 val)
> > +{
> > + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > +
> > + if ((cgrp->parent == NULL) || (val > 100))
> > + return -EINVAL;
> > +
> > + spin_lock(&memcg->reclaim_param_lock);
> > + memcg->dirty_ratio = val;
> > + memcg->dirty_bytes = 0;
> > + spin_unlock(&memcg->reclaim_param_lock);
> > +
> > + return 0;
> > +}
> > +
> > +static u64 mem_cgroup_dirty_bytes_read(struct cgroup *cgrp, struct cftype *cft)
> > +{
> > + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > +
> > + return get_dirty_param(memcg, MEM_CGROUP_DIRTY_BYTES);
> > +}
> > +
> > +static int
> > +mem_cgroup_dirty_bytes_write(struct cgroup *cgrp, struct cftype *cft, u64 val)
> > +{
> > + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > +
> > + if (cgrp->parent == NULL)
> > + return -EINVAL;
> > +
> > + spin_lock(&memcg->reclaim_param_lock);
> > + memcg->dirty_ratio = 0;
> > + memcg->dirty_bytes = val;
> > + spin_unlock(&memcg->reclaim_param_lock);
> > +
> > + return 0;
> > +}
> > +
> > +static u64
> > +mem_cgroup_dirty_background_ratio_read(struct cgroup *cgrp, struct cftype *cft)
> > +{
> > + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > +
> > + return get_dirty_param(memcg, MEM_CGROUP_DIRTY_BACKGROUND_RATIO);
> > +}
> > +
> > +static int mem_cgroup_dirty_background_ratio_write(struct cgroup *cgrp,
> > + struct cftype *cft, u64 val)
> > +{
> > + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > +
> > + if ((cgrp->parent == NULL) || (val > 100))
> > + return -EINVAL;
> > +
> > + spin_lock(&memcg->reclaim_param_lock);
> > + memcg->dirty_background_ratio = val;
> > + memcg->dirty_background_bytes = 0;
> > + spin_unlock(&memcg->reclaim_param_lock);
> > +
> > + return 0;
> > +}
> > +
> > +static u64
> > +mem_cgroup_dirty_background_bytes_read(struct cgroup *cgrp, struct cftype *cft)
> > +{
> > + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > +
> > + return get_dirty_param(memcg, MEM_CGROUP_DIRTY_BACKGROUND_BYTES);
> > +}
> > +
> > +static int mem_cgroup_dirty_background_bytes_write(struct cgroup *cgrp,
> > + struct cftype *cft, u64 val)
> > +{
> > + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > +
> > + if (cgrp->parent == NULL)
> > + return -EINVAL;
> > +
> > + spin_lock(&memcg->reclaim_param_lock);
> > + memcg->dirty_background_ratio = 0;
> > + memcg->dirty_background_bytes = val;
> > + spin_unlock(&memcg->reclaim_param_lock);
> > +
> > + return 0;
> > +}
> > +
> > static struct cftype mem_cgroup_files[] = {
> > {
> > .name = "usage_in_bytes",
> > @@ -3518,6 +3785,26 @@ static struct cftype mem_cgroup_files[] = {
> > .write_u64 = mem_cgroup_swappiness_write,
> > },
> > {
> > + .name = "dirty_ratio",
> > + .read_u64 = mem_cgroup_dirty_ratio_read,
> > + .write_u64 = mem_cgroup_dirty_ratio_write,
> > + },
> > + {
> > + .name = "dirty_bytes",
> > + .read_u64 = mem_cgroup_dirty_bytes_read,
> > + .write_u64 = mem_cgroup_dirty_bytes_write,
> > + },
> > + {
> > + .name = "dirty_background_ratio",
> > + .read_u64 = mem_cgroup_dirty_background_ratio_read,
> > + .write_u64 = mem_cgroup_dirty_background_ratio_write,
> > + },
> > + {
> > + .name = "dirty_background_bytes",
> > + .read_u64 = mem_cgroup_dirty_background_bytes_read,
> > + .write_u64 = mem_cgroup_dirty_background_bytes_write,
> > + },
> > + {
> > .name = "move_charge_at_immigrate",
> > .read_u64 = mem_cgroup_move_charge_read,
> > .write_u64 = mem_cgroup_move_charge_write,
> > @@ -3776,8 +4063,23 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
> > mem->last_scanned_child = 0;
> > spin_lock_init(&mem->reclaim_param_lock);
> >
> > - if (parent)
> > + if (parent) {
> > mem->swappiness = get_swappiness(parent);
> > +
> > + mem->dirty_ratio = get_dirty_param(parent,
> > + MEM_CGROUP_DIRTY_RATIO);
> > + mem->dirty_bytes = get_dirty_param(parent,
> > + MEM_CGROUP_DIRTY_BYTES);
> > + mem->dirty_background_ratio = get_dirty_param(parent,
> > + MEM_CGROUP_DIRTY_BACKGROUND_RATIO);
> > + mem->dirty_background_bytes = get_dirty_param(parent,
> > + MEM_CGROUP_DIRTY_BACKGROUND_BYTES);
> > + } else {
> > + mem->dirty_ratio = vm_dirty_ratio;
> > + mem->dirty_bytes = vm_dirty_bytes;
> > + mem->dirty_background_ratio = vm_dirty_ratio;
> > + mem->dirty_background_bytes = vm_dirty_bytes;
>
> background_dirty_ratio ?

Sounds better.

OK, I'll apply all the changes and post another version.

Thanks!
-Andrea
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Next message: David Rientjes: "[patch] slab: add memory hotplug support"
Previous message: Geert Uytterhoeven: "Re: [PATCH RFC] kconfig: place git SHA1 in .config output if in git tree"
In reply to: Andrea Righi: "Re: [PATCH -mmotm 1/2] memcg: dirty pages accounting and limitinginfrastructure"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]