From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx191.postini.com [74.125.245.191]) by kanga.kvack.org (Postfix) with SMTP id D8F726B0027 for ; Thu, 4 Apr 2013 21:09:34 -0400 (EDT) Received: by mail-ie0-f202.google.com with SMTP id qd14so795867ieb.5 for ; Thu, 04 Apr 2013 18:09:34 -0700 (PDT) From: Greg Thelen Subject: Re: [PATCH v2 03/28] dcache: convert dentry_stat.nr_unused to per-cpu counters References: <1364548450-28254-1-git-send-email-glommer@parallels.com> <1364548450-28254-4-git-send-email-glommer@parallels.com> Date: Thu, 04 Apr 2013 18:09:31 -0700 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, containers@lists.linux-foundation.org, Michal Hocko , Johannes Weiner , kamezawa.hiroyu@jp.fujitsu.com, Andrew Morton , Dave Shrinnker , hughd@google.com, yinghan@google.com, Dave Chinner On Fri, Mar 29 2013, Glauber Costa wrote: > From: Dave Chinner > > Before we split up the dcache_lru_lock, the unused dentry counter > needs to be made independent of the global dcache_lru_lock. Convert > it to per-cpu counters to do this. > > Signed-off-by: Dave Chinner > Reviewed-by: Christoph Hellwig > --- > fs/dcache.c | 17 ++++++++++++++--- > 1 file changed, 14 insertions(+), 3 deletions(-) > > diff --git a/fs/dcache.c b/fs/dcache.c > index fbfae008..f1196f2 100644 > --- a/fs/dcache.c > +++ b/fs/dcache.c > @@ -118,6 +118,7 @@ struct dentry_stat_t dentry_stat = { > }; > > static DEFINE_PER_CPU(unsigned int, nr_dentry); > +static DEFINE_PER_CPU(unsigned int, nr_dentry_unused); > > #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) > static int get_nr_dentry(void) > @@ -129,10 +130,20 @@ static int get_nr_dentry(void) > return sum < 0 ? 0 : sum; > } > > +static int get_nr_dentry_unused(void) > +{ > + int i; > + int sum = 0; > + for_each_possible_cpu(i) > + sum += per_cpu(nr_dentry_unused, i); > + return sum < 0 ? 0 : sum; > +} Just checking... If cpu x is removed, then its per cpu nr_dentry_unused count survives so we don't leak nr_dentry_unused. Right? I see code in percpu_counter_sum_positive() to explicitly handle this case and I want to make sure we don't need it here. [snip] -- 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: email@kvack.org