Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753953AbcCAOBi (ORCPT ); Tue, 1 Mar 2016 09:01:38 -0500 Received: from mail-wm0-f44.google.com ([74.125.82.44]:38293 "EHLO mail-wm0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753740AbcCAOBh (ORCPT ); Tue, 1 Mar 2016 09:01:37 -0500 Date: Tue, 1 Mar 2016 15:01:34 +0100 From: Michal Hocko To: Vladimir Davydov Cc: Andrew Morton , Tetsuo Handa , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -mm] oom: make oom_reaper_list single linked Message-ID: <20160301140133.GG9461@dhcp22.suse.cz> References: <1456824500-30661-1-git-send-email-vdavydov@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1456824500-30661-1-git-send-email-vdavydov@virtuozzo.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2395 Lines: 77 On Tue 01-03-16 12:28:20, Vladimir Davydov wrote: > Entries are only added/removed from oom_reaper_list at head so we can > use a single linked list and hence save a word in task_struct. There was a larger hole when I've checked the last time but why not. > Signed-off-by: Vladimir Davydov Acked-by: Michal Hocko Thanks! > --- > include/linux/sched.h | 2 +- > mm/oom_kill.c | 15 +++++++-------- > 2 files changed, 8 insertions(+), 9 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 2118e963fba7..7b76e65595c3 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1853,7 +1853,7 @@ struct task_struct { > #endif > int pagefault_disabled; > #ifdef CONFIG_MMU > - struct list_head oom_reaper_list; > + struct task_struct *oom_reaper_list; > #endif > /* CPU-specific state of this task */ > struct thread_struct thread; > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 5d5eca9d6737..1a91d9a26bc9 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -423,7 +423,7 @@ bool oom_killer_disabled __read_mostly; > */ > static struct task_struct *oom_reaper_th; > static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait); > -static LIST_HEAD(oom_reaper_list); > +static struct task_struct *oom_reaper_list; > static DEFINE_SPINLOCK(oom_reaper_lock); > > > @@ -530,13 +530,11 @@ static int oom_reaper(void *unused) > while (true) { > struct task_struct *tsk = NULL; > > - wait_event_freezable(oom_reaper_wait, > - (!list_empty(&oom_reaper_list))); > + wait_event_freezable(oom_reaper_wait, oom_reaper_list != NULL); > spin_lock(&oom_reaper_lock); > - if (!list_empty(&oom_reaper_list)) { > - tsk = list_first_entry(&oom_reaper_list, > - struct task_struct, oom_reaper_list); > - list_del(&tsk->oom_reaper_list); > + if (oom_reaper_list != NULL) { > + tsk = oom_reaper_list; > + oom_reaper_list = tsk->oom_reaper_list; > } > spin_unlock(&oom_reaper_lock); > > @@ -555,7 +553,8 @@ static void wake_oom_reaper(struct task_struct *tsk) > get_task_struct(tsk); > > spin_lock(&oom_reaper_lock); > - list_add(&tsk->oom_reaper_list, &oom_reaper_list); > + tsk->oom_reaper_list = oom_reaper_list; > + oom_reaper_list = tsk; > spin_unlock(&oom_reaper_lock); > wake_up(&oom_reaper_wait); > } > -- > 2.1.4 -- Michal Hocko SUSE Labs