Re: [PATCH 7/7] memcg: freeing page_cgroup at suitable chance

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Mon, 17 Mar 2008 12:10:40 +0900
Li Zefan <lizf@cn.fujitsu.com> wrote:

> > +void try_to_shrink_page_cgroup(struct page *page, int order);
> > +
> 
> extern void
> 
ok.

> >  #else
> >  
> > -static struct page_cgroup *
> > +static inline struct page_cgroup *
> >  get_page_cgroup(struct page *page, gfp_t gfpmask, bool allocate)
> >  {
> >  	return NULL;
> >  }
> > +static inline void try_to_shrink_page_cgroup(struct page *page, int order)
> > +{
> > +	return;
> > +}
> > +#define PCGRP_SHRINK_ORDER	(MAX_ORDER)
> >  #endif
> >  #endif
> > Index: mm-2.6.25-rc5-mm1/mm/page_cgroup.c
> > ===================================================================
> > --- mm-2.6.25-rc5-mm1.orig/mm/page_cgroup.c
> > +++ mm-2.6.25-rc5-mm1/mm/page_cgroup.c
> > @@ -12,6 +12,7 @@
> >   */
> >  
> >  #include <linux/mm.h>
> > +#include <linux/mmzone.h>
> >  #include <linux/slab.h>
> >  #include <linux/radix-tree.h>
> >  #include <linux/memcontrol.h>
> > @@ -80,6 +81,7 @@ static void save_result(struct page_cgro
> >  	pcp = &__get_cpu_var(pcpu_page_cgroup_cache);
> >  	pcp->ents[hash].idx = idx;
> >  	pcp->ents[hash].base = base;
> > +	smp_wmb();
> 
> Whenever you add a memory barrier, you should comment on it.
> 
ok.

> >  	preempt_enable();
> >  }
> >  
> > @@ -156,6 +158,58 @@ out:
> >  	return pc;
> >  }
> >  
> > +/* Must be called under zone->lock */
> > +void try_to_shrink_page_cgroup(struct page *page, int order)
> > +{
> > +	unsigned long pfn = page_to_pfn(page);
> > +	int nid = page_to_nid(page);
> > +	int idx = pfn >> PCGRP_SHIFT;
> > +	int hnum = (PAGE_CGROUP_NR_CACHE - 1);
> > +	struct page_cgroup_cache *pcp;
> > +	struct page_cgroup_head *head;
> > +	struct page_cgroup_root *root;
> > +	unsigned long end_pfn;
> > +	int cpu;
> > +
> > +
> 
> redundant empty line
> 
> > +	root = root_dir[nid];
> > +	if (!root || in_interrupt() || (order < PCGRP_SHIFT))
> > +		return;
> > +
> > +	pfn = page_to_pfn(page);
> > +	end_pfn = pfn + (1 << order);
> > +
> > +	while (pfn != end_pfn) {
> > +		idx = pfn >> PCGRP_SHIFT;
> > +		/* Is this pfn has entry ? */
> > +		rcu_read_lock();
> > +		head = radix_tree_lookup(&root->root_node, idx);
> > +		rcu_read_unlock();
> > +		if (!head) {
> > +			pfn += (1 << PCGRP_SHIFT);
> 
> pfn += PCGRP_SIZE;
> 
ok.

> > +			continue;
> > +		}
> > +		/* It's guaranteed that no one access to this pfn/idx
> > +		   because there is no reference to this page. */
> > +		hnum = (idx) & (PAGE_CGROUP_NR_CACHE - 1);
> > +		for_each_online_cpu(cpu) {
> > +			pcp = &per_cpu(pcpu_page_cgroup_cache, cpu);
> > +			smp_rmb();
> > +			if (pcp->ents[hnum].idx == idx)
> > +				pcp->ents[hnum].base = NULL;
> > +		}
> > +		if (spin_trylock(&root->tree_lock)) {
> > +			/* radix tree is freed by RCU. so they will not call
> > +			   free_pages() right now.*/
> > +			radix_tree_delete(&root->root_node, idx);
> > +			spin_unlock(&root->tree_lock);
> > +			/* We can free this in lazy fashion .*/
> > +			free_page_cgroup(head);
> > +		}
> > +		pfn += (1 << PCGRP_SHIFT);
> 
> ditto
> 
ok.

Thanks,
-Kame

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>