Re: [BUG nohz]: wrong user and system time accounting

Frederic Weisbecker
2017-04-12T15:14:30Z

On Wed, Apr 12, 2017 at 04:57:58PM +0200, Thomas Gleixner wrote:
> On Wed, 12 Apr 2017, Frederic Weisbecker wrote:
> > On Tue, Apr 11, 2017 at 04:22:48PM +0200, Thomas Gleixner wrote:
> > > It's not different from the current jiffies based stuff at all. Same
> > > failure mode.
> >
> > Yes you're right, I got confused again. So to fix this we could do our snapshots
> > at a frequency lower than HZ but still high enough to avoid overhead.
> >
> > Something like TICK_NSEC / 2 ?
>
> If you are using TSC anyway then you can do proper accumulation for both
> system and user and only account the data when the accumulation is more
> than a jiffie.

Sounds nice, and accumulation shouldn't introduce too much overhead. Let's try that.

Thanks.

>
> Thanks,
>
> tglx
>