linux-kernel - Re: [tip:timers/urgent] ktime: Get rid of the union

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Message-ID: <alpine.DEB.2.20.1701040953140.3620@nanos>
Date:   Wed, 4 Jan 2017 09:54:12 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Peter Zijlstra <peterz@...radead.org>
cc:     linux-kernel@...r.kernel.org, mingo@...nel.org, hpa@...or.com,
        linux-tip-commits@...r.kernel.org
Subject: Re: [tip:timers/urgent] ktime: Get rid of the union

On Tue, 3 Jan 2017, Peter Zijlstra wrote:

> On Sun, Dec 25, 2016 at 05:26:33AM -0800, tip-bot for Thomas Gleixner wrote:
> > Commit-ID:  64dac5c9e0f5a933e4520f0cb689b7b143925207
> > Gitweb:     http://git.kernel.org/tip/64dac5c9e0f5a933e4520f0cb689b7b143925207
> > Author:     Thomas Gleixner <tglx@...utronix.de>
> > AuthorDate: Sun, 25 Dec 2016 11:38:40 +0100
> > Committer:  Thomas Gleixner <tglx@...utronix.de>
> > CommitDate: Sun, 25 Dec 2016 13:11:50 +0100
> > 
> > ktime: Get rid of the union
> > 
> > ktime is a union because the initial implementation stored the time in
> > scalar nanoseconds on 64 bit machine and in a endianess optimized timespec
> > variant for 32bit machines. The Y2038 cleanup removed the timespec variant
> > and switched everything to scalar nanoseconds. The union remained, but
> > become completely pointless.
> > 
> > Get rid of the union and just keep ktime_t as simple typedef of type s64.
> 
> All good stuff. One question that remains is why keep the type while
> removing the cycles_t type?

That would have been a massive surgery which I was not able to pull off on
top of the other changes.

Thanks,

	tglx