[Devel] Re: [PATCH] memcg: reduce size of per-cpu-stat to be appropriate size.

[KAMEZAWA Hiroyuki]

On Fri, 14 Nov 2008 13:13:29 +0530
Balbir Singh <balbir at linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > How about this one ?
> > tested on x86-64 + mmotm-Nov10, works well. 
> > (test on other arch is welcome.)
> > 
> > -Kame
> > ==
> > As  Jan Blunck <jblunck at suse.de> pointed out, allocating
> > per-cpu stat for memcg to the size of NR_CPUS is not good.
> > 
> > This patch changes mem_cgroup's cpustat allocation not based
> > on NR_CPUS but based on nr_cpu_ids.
> > 
> > From: Jan Blunck <jblunck at suse.de>
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
> > 
> > ---
> >  mm/memcontrol.c |   34 ++++++++++++++++++----------------
> >  1 file changed, 18 insertions(+), 16 deletions(-)
> > 
> > Index: mmotm-2.6.28-Nov10/mm/memcontrol.c
> > ===================================================================
> > --- mmotm-2.6.28-Nov10.orig/mm/memcontrol.c
> > +++ mmotm-2.6.28-Nov10/mm/memcontrol.c
> > @@ -60,7 +60,7 @@ struct mem_cgroup_stat_cpu {
> >  } ____cacheline_aligned_in_smp;
> > 
> >  struct mem_cgroup_stat {
> > -	struct mem_cgroup_stat_cpu cpustat[NR_CPUS];
> > +	struct mem_cgroup_stat_cpu cpustat[0];
> >  };
> > 
> >  /*
> > @@ -129,11 +129,10 @@ struct mem_cgroup {
> > 
> >  	int	prev_priority;	/* for recording reclaim priority */
> >  	/*
> > -	 * statistics.
> > +	 * statistics. This must be placed at the end of memcg.
> >  	 */
> >  	struct mem_cgroup_stat stat;
> >  };
> > -static struct mem_cgroup init_mem_cgroup;
> > 
> >  enum charge_type {
> >  	MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
> > @@ -1292,42 +1291,45 @@ static void free_mem_cgroup_per_zone_inf
> >  	kfree(mem->info.nodeinfo[node]);
> >  }
> > 
> > +static int mem_cgroup_size(void)
> 
> inline this function?
> 
necessary ? 

> Other than that, I think the cont->parent check for freeing has already been
> spotted and pointed out
> 
Ah, yes. fixed in v2.

Thanks,
-Kame

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