Re: dynamic-hz

[Pavel Machek <pavel@suse.cz>]

Hi!

> > > > > > But that does not matter, right? Yes, one-shot timer will not fire
> > > > > > exactly at right place, but as long as you are reading TSC and basing
> > > > > > next shot on current time, error should not accumulate.
> > > > > 
> > > > > As said in the rest of the message, the error (or some other error)
> > > > > accumulates heavily today in the tick-loss compensation/adjustment
> > > > > algorithm in arch/i386/kernel/timers/timer_tsc.c, so I'm sceptical
> > > > > about
> > > > 
> > > > I do not see how it should accumulate. Lets have working TSC. You want
> > > > to emulate fixed-period timer with single-shot timer.
> > > 
> > > Its caused by the fact that we don't use the the TSC to accumulate time.
> > > We are instead interpolating between timer ticks and the TSC, where
> > 
> > Yes, it was supposed to be simple, so that Andrea understands that
> > there's nothing inherently broken with single-shot timers.
> 
> Just a quick comment; The timer does not need to be single-shot 
> all the time, it can be a combination of continuous and variable
> length timer, and it can change depending on the system load.
> 
> We recently added VST support for OMAP in linux-omap bk tree, and 
> made some changes to the previous VST implementations that might be
> of interest:
...
> The patch in question is at:
> 
> http://linux-omap.bkbits.net:8080/main/user=tmlind/patch@1.2016.4.18?nav=!-|index.html|stats|!+|index.html|ChangeSet@-12w|cset@1.2016.4.18

Wow, that's basically 8 lines of code plus driver for new
hardware... Is it really that simple?
								Pavel
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