From: Cody P Schafer <cody@linux.vnet.ibm.com>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/4] mmzone: note that node_size_lock should be manipulated via pgdat_resize_lock()
Date: Wed, 01 May 2013 15:47:59 -0700 [thread overview]
Message-ID: <51819B9F.3090407@linux.vnet.ibm.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1305011541260.8804@chino.kir.corp.google.com>
On 05/01/2013 03:42 PM, David Rientjes wrote:
> On Wed, 1 May 2013, Cody P Schafer wrote:
>
>>>> Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
>>>
>>> Nack, pgdat_resize_unlock() is unnecessary if irqs are known to be
>>> disabled.
>>>
>>
>> All this patch does is is indicate that rather than using node_size_lock
>> directly (as it won't be around without CONFIG_MEMORY_HOTPLUG), one should use
>> the pgdat_resize_[un]lock() helper macros.
>>
>
> I think that's obvious given the lock is surrounded by
> #ifdef CONFIG_MEMORY_HOTPLUG. The fact remains that hotplug code need not
> use pgdat_resize_lock() if irqs are disabled.
>
Obvious how? This comment is the documentation on how to handle locking
of pg_data_t, and doesn't mention pgdat_resize_lock() at all. Sure, a
newcomer would probably find pgdat_resize_lock() eventually, even more
so if they were interested in performance gains from not re-disabling
local irqs.
I don't see a convincing reason to omit relevant documentation and make
it more difficult to find the "right" way to do things.
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next prev parent reply other threads:[~2013-05-01 22:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-01 22:17 [PATCH 0/4] misc patches related to resizing nodes & zones Cody P Schafer
2013-05-01 22:17 ` [PATCH 1/4] mmzone: make holding lock_memory_hotplug() a requirement for updating pgdat size Cody P Schafer
2013-05-01 22:26 ` David Rientjes
2013-05-01 22:32 ` Cody P Schafer
2013-05-01 22:39 ` David Rientjes
2013-05-01 22:45 ` Cody P Schafer
2013-05-01 22:17 ` [PATCH 2/4] mm: fix comment referring to non-existent size_seqlock, change to span_seqlock Cody P Schafer
2013-05-01 22:27 ` David Rientjes
2013-05-01 22:17 ` [PATCH 3/4] mmzone: note that node_size_lock should be manipulated via pgdat_resize_lock() Cody P Schafer
2013-05-01 22:29 ` David Rientjes
2013-05-01 22:36 ` Cody P Schafer
2013-05-01 22:42 ` David Rientjes
2013-05-01 22:47 ` Cody P Schafer [this message]
2013-05-01 22:17 ` [PATCH 4/4] memory_hotplug: use pgdat_resize_lock() when updating node_present_pages Cody P Schafer
2013-05-01 22:30 ` David Rientjes
2013-05-01 22:41 ` Cody P Schafer
2013-05-01 22:48 ` David Rientjes
2013-05-01 22:51 ` Cody P Schafer
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