Re: [PATCH 0/3] timekeeping: Improved NOHZ frequency steering (v2)

From: Miroslav Lichvar
Date: Tue Jul 08 2014 - 07:08:24 EST

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?


Miroslav Lichvar
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at