Date: Tue, 8 Jul 2014 13:08:16 +0200
From: Miroslav Lichvar <mlichvar@redhat.com>
To: John Stultz <john.stultz@linaro.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
        Richard Cochran <richardcochran@gmail.com>,
        Prarit Bhargava <prarit@redhat.com>
Subject: Re: [PATCH 0/3] timekeeping: Improved NOHZ frequency steering (v2)
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On Mon, May 19, 2014 at 10:57:29AM -0700, John Stultz wrote:
> Another area we have to be careful with is there are still
> architectures (powerpc and ia64) which haven't switched from the old
> vsyscall rounding logic (CONFIG_GENERIC_TIME_VSYSCALL_OLD). In these
> cases we add up to 1ns of error each tick/update as we round up the
> sub-nanoseconds to ensure we don't see inconsistencies.  If the
> adjustment logic can't handle this, I don't want to regress those
> arches.

I spent some time trying to figure out a workaround for the nanosecond
rounding, but I didn't find anything that wouldn't complicate the mult
adjustment logic and bring back the problems which the direct division
approach is supposed to solve.

It seems it may be a while before the old vsyscalls are fixed. How
about including only the first two patches from this set for now?

Thanks,

-- 
Miroslav Lichvar
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