[Devel] Re: Unable to remove control groups on 2.6.23-rc8-mm1

KAMEZAWA Hiroyuki kamezawa.hiroyu at jp.fujitsu.com
Wed Sep 26 14:37:36 PDT 2007


On Wed, 26 Sep 2007 08:46:20 -0700
Badari Pulavarty <pbadari at us.ibm.com> wrote:

> On Wed, 2007-09-26 at 18:14 +0900, KAMEZAWA Hiroyuki wrote:
> > This is an experimental patch for drop pages in empty cgroup.
> > comments ?
> 
> Hmm.. Patch doesn't seems to help :(
> 
> elm3b155:/dev/cgroup/xxx # cat memory.usage_in_bytes
> 65536
> elm3b155:/dev/cgroup/xxx # sync
> elm3b155:/dev/cgroup/xxx # sync
> elm3b155:/dev/cgroup/xxx # cat memory.usage_in_bytes
> 65536
> 
sorry for no explanation.

try
==
%sync
%echo -n 1 > /path_to_group/memory.drop_in_force // drop all rmaining pages.
==

Anyway I'll brush up it and post again.

Thanks,
-Kame


> Thanks,
> Badari
> 
> > 
> > ==
> > An experimental patch.
> > 
> > Drop all pages in memcontrol cgroup if cgroup's task is empty.
> > Please type "sync" before try to drop. Unless sync, maybe -EBUSY will return.
> > 
> > Problem: not handle mlocked pages now.
> > 
> > 
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
> > 
> > ---
> >  include/linux/memcontrol.h |   13 ++++-
> >  mm/memcontrol.c            |  113 +++++++++++++++++++++++++++++++++++++++++++++
> >  mm/vmscan.c                |   16 +++++-
> >  3 files changed, 140 insertions(+), 2 deletions(-)
> > 
> > Index: linux-2.6.23-rc8-mm1/mm/memcontrol.c
> > ===================================================================
> > --- linux-2.6.23-rc8-mm1.orig/mm/memcontrol.c
> > +++ linux-2.6.23-rc8-mm1/mm/memcontrol.c
> > @@ -63,6 +63,7 @@ struct mem_cgroup {
> >  	 */
> >  	spinlock_t lru_lock;
> >  	unsigned long control_type;	/* control RSS or RSS+Pagecache */
> > +	unsigned long force_drop;
> >  };
> > 
> >  /*
> > @@ -135,6 +136,31 @@ static inline int page_cgroup_locked(str
> >  					&page->page_cgroup);
> >  }
> > 
> > +static inline unsigned long long mem_cgroup_usage(struct mem_cgroup *mem)
> > +{
> > +	return mem->res.usage;
> > +}
> > +
> > +int mem_cgroup_reclaim_end(struct mem_cgroup *mem)
> > +{
> > +	if (!mem)
> > +		return 0;
> > +	if (mem_cgroup_usage(mem) == 0)
> > +		return 1;
> > +	return 0;
> > +}
> > +
> > +int mem_cgroup_force_reclaim(struct mem_cgroup *mem)
> > +{
> > +	if (!mem)
> > +		return 0;
> > +	/* Need more precise check if LRU is separated. */
> > +	if (mem->force_drop)
> > +		return 1;
> > +	else
> > +		return 0;
> > +}
> > +
> >  void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
> >  {
> >  	int locked;
> > @@ -437,6 +463,52 @@ void mem_cgroup_uncharge(struct page_cgr
> >  	}
> >  }
> > 
> > +/*
> > + * Drop all pages
> > + * # of tasks in this cgroup must be 0 before call this.
> > + */
> > +int mem_cgroup_drop(struct mem_cgroup *mem)
> > +{
> > +
> > +	unsigned long long before;
> > +	struct cgroup *cg = mem->css.cgroup;
> > +	int ret = -EBUSY;
> > +	unsigned long expire = jiffies + 30 * HZ; /* just pseudo value */
> > +
> > +	css_get(&mem->css);
> > +retry:
> > +	/* disallow if there is the task. */
> > +	if (atomic_read(&cg->count))
> > +		goto end;
> > +	/*
> > +	 * We have to call try_to_free_mem_cgroup_pages() several times.
> > +	 * Especially when there is write-back pages.
> > +	 */
> > +	if (time_after(jiffies, expire))
> > +		goto end;
> > +
> > +	before = mem_cgroup_usage(mem);
> > +
> > +	if (before == 0) {
> > +		ret = 0;
> > +		goto end;
> > +	}
> > +	mem->force_drop = 1;
> > +	if (try_to_free_mem_cgroup_pages(mem, GFP_HIGHUSER_MOVABLE) == 0)
> > +		congestion_wait(WRITE, HZ/10);
> > +	mem->force_drop = 0;
> > +
> > +	/* made some progress */
> > +	if (mem_cgroup_usage(mem) <= before)
> > +		goto retry;
> > +
> > +end:
> > +	css_put(&mem->css);
> > +	return ret;
> > +}
> > +
> > +
> > +
> >  int mem_cgroup_write_strategy(char *buf, unsigned long long *tmp)
> >  {
> >  	*tmp = memparse(buf, &buf);
> > @@ -522,6 +594,41 @@ static ssize_t mem_control_type_read(str
> >  			ppos, buf, s - buf);
> >  }
> > 
> > +static ssize_t mem_drop_type_write(struct cgroup *cont,
> > +			struct cftype *cft, struct file *file,
> > +			const char __user *userbuf,
> > +			size_t nbytes, loff_t *pos)
> > +{
> > +	struct mem_cgroup *mem;
> > +	int ret;
> > +	char *buf, *end;
> > +	unsigned long tmp;
> > +
> > +	mem = mem_cgroup_from_cont(cont);
> > +	buf = kmalloc(nbytes + 1, GFP_KERNEL);
> > +	ret = -ENOMEM;
> > +	if (buf == NULL)
> > +		goto out;
> > +	buf[nbytes] = 0;
> > +	ret = -EFAULT;
> > +	if (copy_from_user(buf, userbuf, nbytes))
> > +		goto out_free;
> > +	ret = -EINVAL;
> > +	tmp = simple_strtoul(buf, &end, 10);
> > +
> > +	if (*end != '\0')
> > +		goto out_free;
> > +	if (tmp) {
> > +		ret = mem_cgroup_drop(mem);
> > +		if (!ret)
> > +			ret = nbytes;
> > +	}
> > +out_free:
> > +	kfree(buf);
> > +out:
> > +	return ret;
> > +}
> > +
> >  static struct cftype mem_cgroup_files[] = {
> >  	{
> >  		.name = "usage_in_bytes",
> > @@ -544,6 +651,11 @@ static struct cftype mem_cgroup_files[] 
> >  		.write = mem_control_type_write,
> >  		.read = mem_control_type_read,
> >  	},
> > +	{
> > +		.name = "drop_in_force",
> > +		.write = mem_drop_type_write,
> > +		.read = mem_cgroup_read,
> > +	},
> >  };
> > 
> >  static struct mem_cgroup init_mem_cgroup;
> > @@ -567,6 +679,7 @@ mem_cgroup_create(struct cgroup_subsys *
> >  	INIT_LIST_HEAD(&mem->inactive_list);
> >  	spin_lock_init(&mem->lru_lock);
> >  	mem->control_type = MEM_CGROUP_TYPE_ALL;
> > +	mem->force_drop = 0;
> >  	return &mem->css;
> >  }
> > 
> > Index: linux-2.6.23-rc8-mm1/include/linux/memcontrol.h
> > ===================================================================
> > --- linux-2.6.23-rc8-mm1.orig/include/linux/memcontrol.h
> > +++ linux-2.6.23-rc8-mm1/include/linux/memcontrol.h
> > @@ -47,6 +47,10 @@ extern int mem_cgroup_cache_charge(struc
> >  					gfp_t gfp_mask);
> >  extern struct mem_cgroup *mm_cgroup(struct mm_struct *mm);
> > 
> > +/* called when page reclaim has no progress in mem cgroup */
> > +extern int mem_cgroup_reclaim_end(struct mem_cgroup *mem);
> > +extern int mem_cgroup_force_reclaim(struct mem_cgroup *mem);
> > +
> >  static inline void mem_cgroup_uncharge_page(struct page *page)
> >  {
> >  	mem_cgroup_uncharge(page_get_page_cgroup(page));
> > @@ -102,7 +106,14 @@ static inline struct mem_cgroup *mm_cgro
> >  {
> >  	return NULL;
> >  }
> > -
> > +static inline int mem_cgroup_force_reclaim(struct mem_cgroup *mem)
> > +{
> > +	return 0;
> > +}
> > +static inline int mem_cgroup_reclaim_end(struct mem_cgroup *mem)
> > +{
> > +	return 0;
> > +}
> >  #endif /* CONFIG_CGROUP_MEM_CONT */
> > 
> >  #endif /* _LINUX_MEMCONTROL_H */
> > Index: linux-2.6.23-rc8-mm1/mm/vmscan.c
> > ===================================================================
> > --- linux-2.6.23-rc8-mm1.orig/mm/vmscan.c
> > +++ linux-2.6.23-rc8-mm1/mm/vmscan.c
> > @@ -1168,6 +1168,13 @@ static unsigned long shrink_zone(int pri
> >  		zone->nr_scan_inactive = 0;
> >  	else
> >  		nr_inactive = 0;
> > +	/* TODO: we need to know # of pages to be reclaimed per group */
> > +	if (mem_cgroup_force_reclaim(sc->mem_cgroup)) {
> > +		if (!nr_active)
> > +			nr_active = sc->swap_cluster_max;
> > +		if (!nr_inactive)
> > +			nr_inactive = sc->swap_cluster_max;
> > +	}
> > 
> >  	while (nr_active || nr_inactive) {
> >  		if (nr_active) {
> > @@ -1256,6 +1263,7 @@ static unsigned long do_try_to_free_page
> >  	int ret = 0;
> >  	unsigned long total_scanned = 0;
> >  	unsigned long nr_reclaimed = 0;
> > +	unsigned long progress;
> >  	struct reclaim_state *reclaim_state = current->reclaim_state;
> >  	unsigned long lru_pages = 0;
> >  	int i;
> > @@ -1276,7 +1284,8 @@ static unsigned long do_try_to_free_page
> >  		sc->nr_scanned = 0;
> >  		if (!priority)
> >  			disable_swap_token();
> > -		nr_reclaimed += shrink_zones(priority, zones, sc);
> > +		progress = shrink_zones(priority, zones, sc);
> > +		nr_reclaimed += progress;
> >  		/*
> >  		 * Don't shrink slabs when reclaiming memory from
> >  		 * over limit cgroups
> > @@ -1292,6 +1301,11 @@ static unsigned long do_try_to_free_page
> >  			ret = 1;
> >  			goto out;
> >  		}
> > +		if (progress == 0 &&
> > +		    mem_cgroup_reclaim_end(sc->mem_cgroup)) {
> > +			ret = 1;
> > +			goto out;
> > +		}
> > 
> >  		/*
> >  		 * Try to write back as many pages as we just scanned.  This
> > 
> 
> 
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