linux-kernel - Re: [patch] x86: set hotpluggable nodes in nodes_possible

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Message-ID: <alpine.DEB.2.00.1001202344580.29982@chino.kir.corp.google.com>
Date:	Wed, 20 Jan 2010 23:50:54 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Haicheng Li <haicheng.li@...ux.intel.com>
cc:	Ingo Molnar <mingo@...hat.com>, Yinghai Lu <yinghai@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org
Subject: Re: [patch] x86: set hotpluggable nodes in nodes_possible_map

On Thu, 21 Jan 2010, Haicheng Li wrote:

> > Nack, we don't need to add yet another nodemask because you're having
> > trouble finding a new name for a cpu_nodes_parsed.  It would be perfectly 
> Hey Dave, why do you think it's just a naming issue?
> 
> What I'm concerning is that your assumption of cpu_nodes_parsed use is wrong,
> cpu_nodes_parsed is needed anyway since its semantics represent the node with
> cpu affinity rather than memless node, that's also why I originally doubted
> cpu_node_parsed cannot handle hotplug node.

Wrong, cpu_nodes_parsed (despite its name) solely represents nodes that do 
not have online address memory ranges.  That's it.  Nothing more, nothing 
less.  That's why I suggest you rename it to no_mem_nodes or something 
similar.  Look at the single time that the nodemask is used: to set 
cleared bits in node_possible_map that were not set in nodes_parsed 
because THEY DO NOT HAVE ASSOCIATED ONLINE MEMORY RANGES, the _only_ time 
a node gets set in nodes_parsed.

Once you rename nodes_parsed to mem_nodes and cpu_nodes_parsed to 
no_mem_nodes, it may become clearer.

> we also need hp_nodes_parsed to represent the node with hotpluggable memory
> region, just like why we need nodes_parsed to repsent node with mem on.
> 

It's pointless to add another nodemask, the semantics of cpu_nodes_parsed 
is perfectly legitimate for hotpluggable nodes as well.  Instead of 
fixating on the name, look at the code that uses it.
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