On Tue, Jun 19, 2018 at 09:39:02AM +0800, Jin, Yao wrote: > > > On 6/18/2018 6:45 PM, Peter Zijlstra wrote: > > On Mon, Jun 18, 2018 at 02:55:32PM +0800, Jin, Yao wrote: > > > Thanks for providing the patch. I understand this approach. > > > > > > In my opinion, the skid window is from counter overflow to interrupt > > > delivered. While if the skid window is too *big* (e.g. user -> kernel), it > > > should be not very useful. So personally, I'd prefer to drop the samples. > > > > I really don't get your insitence on dropping the sample. Dropping > > samples is bad. Furthermore, doing what Mark suggests actually improves > > the result by reducing the skid, if the event happened before we entered > > (as it damn well should) then the user regs, which point at the entry > > site, are a better approximation than our in-kernel set. > > > > So not only do you not loose the sample, you actually get a better > > sample. > > > > OK, that's fine, thanks! > > I guess Mark will post this patch, right?
I'll try to spin something shortly -- I'm just figuring out how this should work with guest sampling. Thanks, Mark.
