Messages in this thread | | | Date | Wed, 16 Jul 2014 08:59:07 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH 0/3] timekeeping: Improved NOHZ frequency steering (v2) |
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On Tue, 15 Jul 2014, John Stultz wrote:
> On 07/08/2014 04:08 AM, Miroslav Lichvar wrote: > > 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? > > Hey! Sorry for the slow response here, I was on the road the last two weeks. > > So thanks for the ping here. If you're happy with the first two as an > initial step, I'd be willing to try to push those in. The only trouble > is there's a whole lot of timekeeping churn headed for 3.17 that Thomas > has cooked up. While there isn't likely to be direct conflicts in the > changes, I get nervous about mixing too many changes in subtle code at once. > > But maybe I'm being overly cautious? > > Thomas: Would you be ok if I push you some patches to improve ntp/ptp > freq steering w/ NOHZ for this merge window as well? So far the patches > have only shown nice improvements and no regressions, but its clearly > subtle code, and there's a lot going on in this merge window.
I think it's ok. The steering is orthogonal to the other stuff cooking.
Thanks,
tglx
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