From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kamezawa Hiroyuki Subject: Re: [PATCH -V8 11/16] hugetlb/cgroup: Add charge/uncharge routines for hugetlb cgroup Date: Tue, 12 Jun 2012 17:08:25 +0900 Message-ID: <4FD6F8F9.2040901@jp.fujitsu.com> References: <1339232401-14392-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1339232401-14392-12-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1339232401-14392-12-git-send-email-aneesh.kumar-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: "Aneesh Kumar K.V" Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, dhillf-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, mhocko-AlSwsSmVLrQ@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org (2012/06/09 17:59), Aneesh Kumar K.V wrote: > From: "Aneesh Kumar K.V" > > This patchset add the charge and uncharge routines for hugetlb cgroup. > This will be used in later patches when we allocate/free HugeTLB > pages. > > Signed-off-by: Aneesh Kumar K.V I'm sorry if following has been already pointed out. > --- > mm/hugetlb_cgroup.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 87 insertions(+) > > diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c > index 20a32c5..48efd5a 100644 > --- a/mm/hugetlb_cgroup.c > +++ b/mm/hugetlb_cgroup.c > @@ -105,6 +105,93 @@ static int hugetlb_cgroup_pre_destroy(struct cgroup *cgroup) > return -EBUSY; > } > > +int hugetlb_cgroup_charge_page(int idx, unsigned long nr_pages, > + struct hugetlb_cgroup **ptr) > +{ > + int ret = 0; > + struct res_counter *fail_res; > + struct hugetlb_cgroup *h_cg = NULL; > + unsigned long csize = nr_pages * PAGE_SIZE; > + > + if (hugetlb_cgroup_disabled()) > + goto done; > + /* > + * We don't charge any cgroup if the compound page have less > + * than 3 pages. > + */ > + if (hstates[idx].order< 2) > + goto done; > +again: > + rcu_read_lock(); > + h_cg = hugetlb_cgroup_from_task(current); > + if (!h_cg) > + h_cg = root_h_cgroup; > + > + if (!css_tryget(&h_cg->css)) { > + rcu_read_unlock(); > + goto again; > + } > + rcu_read_unlock(); > + > + ret = res_counter_charge(&h_cg->hugepage[idx], csize,&fail_res); > + css_put(&h_cg->css); > +done: > + *ptr = h_cg; > + return ret; > +} > + Memory cgroup uses very complicated 'charge' routine for handling pageout... which gets sleep. For hugetlbfs, it has not sleep routine, you can do charge in simple way. I guess...get/put here is overkill. For example, h_cg cannot be freed while it has tasks. So, if 'current' is belongs to the cgroup, it cannot be disappear. Then, you don't need get/put, additional atomic ops for holding cgroup. rcu_read_lock(); h_cg = hugetlb_cgroup_from_task(current); ret = res_counter_charge(&h_cg->hugetpage[idx], csize, &fail_res); rcu_read_unlock(); return ret; Thanks, -Kame