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Date: Sun, 21 May 2017 09:00:17 +0200
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 2/9] timers: provide a "modern" variant of timers
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To: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>, Thomas Gleixner <tglx@linutronix.de>, Mark Gross <mark.gross@intel.com>, Tejun Heo <tj@kernel.org>, linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, linux-s390 <linux-s390@vger.kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Thu, May 18, 2017 at 10:57:31AM +0200, Arnd Bergmann wrote:
> How expensive would it be to add another field to timer_list and
> just have both pointers?

That would add 4/8 bytes to every structure containing a timer,
so I'd rather avoid it if possible.  But one option might be to
inflict this onto users of outdated compilers and use the union
for modern ones.