Messages in this thread | | | Date | Fri, 28 Jan 2011 08:52:15 +0100 | From | Johannes Weiner <> | Subject | Re: [BUGFIX][PATCH 1/4] memcg: fix limit estimation at reclaim for hugepage |
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On Fri, Jan 28, 2011 at 12:24:49PM +0900, KAMEZAWA Hiroyuki wrote: > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > > Current memory cgroup's code tends to assume page_size == PAGE_SIZE > and arrangement for THP is not enough yet. > > This is one of fixes for supporing THP. This adds > mem_cgroup_check_margin() and checks whether there are required amount of > free resource after memory reclaim. By this, THP page allocation > can know whether it really succeeded or not and avoid infinite-loop > and hangup. > > Total fixes for do_charge()/reclaim memory will follow this patch. > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > --- > include/linux/res_counter.h | 11 +++++++++++ > mm/memcontrol.c | 25 ++++++++++++++++++++++++- > 2 files changed, 35 insertions(+), 1 deletion(-) > > Index: mmotm-0125/include/linux/res_counter.h > =================================================================== > --- mmotm-0125.orig/include/linux/res_counter.h > +++ mmotm-0125/include/linux/res_counter.h > @@ -182,6 +182,17 @@ static inline bool res_counter_check_und > return ret; > } > > +static inline s64 res_counter_check_margin(struct res_counter *cnt) > +{ > + s64 ret; > + unsigned long flags; > + > + spin_lock_irqsave(&cnt->lock, flags); > + ret = cnt->limit - cnt->usage; > + spin_unlock_irqrestore(&cnt->lock, flags); > + return ret; > +}
This function does not check anything. You could name it res_counter_get_margin() e.g. But if you do that, I will complain that it's asymmetric to res_counter_check_under_limit(). And the result will be pretty close to my version...
> @@ -1853,7 +1869,14 @@ static int __mem_cgroup_do_charge(struct > * Check the limit again to see if the reclaim reduced the > * current usage of the cgroup before giving up > */ > - if (ret || mem_cgroup_check_under_limit(mem_over_limit)) > + if (mem_cgroup_check_margin(mem_over_limit) >= csize) > + return CHARGE_RETRY; > + > + /* > + * If the charge size is a PAGE_SIZE, it's not hopeless while > + * we can reclaim a page. > + */ > + if (csize == PAGE_SIZE && ret) > return CHARGE_RETRY;
That makes sense.
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