Message-ID: <1338299468.26856.80.camel@twins>
Subject: Re: [PATCH 14/35] autonuma: knuma_migrated per NUMA node queues
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Hillf Danton <dhillf@gmail.com>, Dan Smith <danms@us.ibm.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
        Paul Turner <pjt@google.com>,
        Suresh Siddha <suresh.b.siddha@intel.com>,
        Mike Galbraith <efault@gmx.de>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Lai Jiangshan <laijs@cn.fujitsu.com>,
        Bharata B Rao <bharata.rao@gmail.com>,
        Lee Schermerhorn <Lee.Schermerhorn@hp.com>,
        Rik van Riel <riel@redhat.com>, Johannes Weiner <hannes@cmpxchg.org>,
        Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
        Christoph Lameter <cl@linux.com>
Date: Tue, 29 May 2012 15:51:08 +0200
In-Reply-To: <1337965359-29725-15-git-send-email-aarcange@redhat.com>
References: <1337965359-29725-1-git-send-email-aarcange@redhat.com>
	 <1337965359-29725-15-git-send-email-aarcange@redhat.com>
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On Fri, 2012-05-25 at 19:02 +0200, Andrea Arcangeli wrote:


> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 41aa49b..8e578e6 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -666,6 +666,12 @@ typedef struct pglist_data {
>  	struct task_struct *kswapd;
>  	int kswapd_max_order;
>  	enum zone_type classzone_idx;
> +#ifdef CONFIG_AUTONUMA
> +	spinlock_t autonuma_lock;
> +	struct list_head autonuma_migrate_head[MAX_NUMNODES];
> +	unsigned long autonuma_nr_migrate_pages;
> +	wait_queue_head_t autonuma_knuma_migrated_wait;
> +#endif
>  } pg_data_t;
>  
>  #define node_present_pages(nid)	(NODE_DATA(nid)->node_present_pages)

O(nr_nodes^2) data.. ISTR people rewriting a certain slab allocator to
get rid of that :-)

Also, don't forget that MAX_NUMNODES is an unconditional 512 on distro
kernels, even when we only have 2.

Now the total wasted space isn't too bad since its only 16 bytes,
totaling a whole 2M for a 256 node system. But still, something like
that wants at least a mention somewhere.


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