From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx103.postini.com [74.125.245.103]) by kanga.kvack.org (Postfix) with SMTP id B24B06B005D for ; Thu, 12 Jul 2012 14:09:41 -0400 (EDT) Date: Thu, 12 Jul 2012 20:08:28 +0200 From: Andrea Arcangeli Subject: Re: [PATCH 20/40] autonuma: alloc/free/init mm_autonuma Message-ID: <20120712180828.GL20382@redhat.com> References: <1340888180-15355-1-git-send-email-aarcange@redhat.com> <1340888180-15355-21-git-send-email-aarcange@redhat.com> <20120630051217.GG3975@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120630051217.GG3975@localhost.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Konrad Rzeszutek Wilk Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Hillf Danton , Dan Smith , Peter Zijlstra , Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Paul Turner , Suresh Siddha , Mike Galbraith , "Paul E. McKenney" , Lai Jiangshan , Bharata B Rao , Lee Schermerhorn , Rik van Riel , Johannes Weiner , Srivatsa Vaddagiri , Christoph Lameter , Alex Shi , Mauricio Faria de Oliveira , Konrad Rzeszutek Wilk , Don Morris , Benjamin Herrenschmidt On Sat, Jun 30, 2012 at 01:12:18AM -0400, Konrad Rzeszutek Wilk wrote: > On Thu, Jun 28, 2012 at 02:56:00PM +0200, Andrea Arcangeli wrote: > > This is where the mm_autonuma structure is being handled. Just like > > sched_autonuma, this is only allocated at runtime if the hardware the > > kernel is running on has been detected as NUMA. On not NUMA hardware > > I think the correct wording is "non-NUMA", not "not NUMA". That sounds far too easy to me, but I've no idea what's the right is here. > > the memory cost is reduced to one pointer per mm. > > > > To get rid of the pointer in the each mm, the kernel can be compiled > > with CONFIG_AUTONUMA=n. > > > > Signed-off-by: Andrea Arcangeli > > --- > > kernel/fork.c | 7 +++++++ > > 1 files changed, 7 insertions(+), 0 deletions(-) > > > > diff --git a/kernel/fork.c b/kernel/fork.c > > index 0adbe09..3e5a0d9 100644 > > --- a/kernel/fork.c > > +++ b/kernel/fork.c > > @@ -527,6 +527,8 @@ static void mm_init_aio(struct mm_struct *mm) > > > > static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) > > { > > + if (unlikely(alloc_mm_autonuma(mm))) > > + goto out_free_mm; > > So reading that I would think that on non-NUMA machines this would fail > (since there is nothing to allocate). But that is not the case > (I hope!?) Perhaps just make the function not return any values? It doesn't fail, it returns 0 on non-NUMA. It's identical to alloc_task_autonuma, per prev email. -- 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