Re: [BUG nohz]: wrong user and system time accounting
From: Frederic Weisbecker
Date: Wed Apr 12 2017 - 11:14:33 EST
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
>