From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx168.postini.com [74.125.245.168]) by kanga.kvack.org (Postfix) with SMTP id D66A86B0062 for ; Fri, 29 Jun 2012 14:07:55 -0400 (EDT) Message-ID: <4FEDEE9F.4080103@redhat.com> Date: Fri, 29 Jun 2012 14:06:23 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH 14/40] autonuma: add page structure fields References: <1340888180-15355-1-git-send-email-aarcange@redhat.com> <1340888180-15355-15-git-send-email-aarcange@redhat.com> In-Reply-To: <1340888180-15355-15-git-send-email-aarcange@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli 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 , Johannes Weiner , Srivatsa Vaddagiri , Christoph Lameter , Alex Shi , Mauricio Faria de Oliveira , Konrad Rzeszutek Wilk , Don Morris , Benjamin Herrenschmidt On 06/28/2012 08:55 AM, Andrea Arcangeli wrote: > On 64bit archs, 20 bytes are used for async memory migration (specific > to the knuma_migrated per-node threads), and 4 bytes are used for the > thread NUMA false sharing detection logic. > > This is a bad implementation due lack of time to do a proper one. It is not ideal, no. If you document what everything does, maybe somebody else will understand the code well enough to help fix it. > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -136,6 +136,32 @@ struct page { > struct page *first_page; /* Compound tail pages */ > }; > > +#ifdef CONFIG_AUTONUMA > + /* > + * FIXME: move to pgdat section along with the memcg and allocate > + * at runtime only in presence of a numa system. > + */ Once you fix it, could you fold the fix into this patch? > + /* > + * To modify autonuma_last_nid lockless the architecture, > + * needs SMP atomic granularity< sizeof(long), not all archs > + * have that, notably some ancient alpha (but none of those > + * should run in NUMA systems). Archs without that requires > + * autonuma_last_nid to be a long. > + */ > +#if BITS_PER_LONG> 32 > + int autonuma_migrate_nid; > + int autonuma_last_nid; > +#else > +#if MAX_NUMNODES>= 32768 > +#error "too many nodes" > +#endif > + /* FIXME: remember to check the updates are atomic */ > + short autonuma_migrate_nid; > + short autonuma_last_nid; > +#endif > + struct list_head autonuma_migrate_node; > +#endif Please document what these fields mean. -- All rights reversed -- 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