Re: [PATCH] x86: Reduce the default HZ value

[Alan Cox]

> IMO, one of the main motives of HRT implementation apart from getting
> higher precision timers was that we now don't necessarily need to rely

Timer frequency and HZ are two entirely different things nowdyas

> on a high timer frequency. If you see problems with Desktop feel and
> responsiveness don't you think there would be other problem which might
> be causing that ?  Your argument about the "desktop feel and
> responsiveness" doesn't explain what actual problem did you see.

People spent months poking at the differences before HZ=1000 became the
default. It wasn't due for amusement values - but this is irrelevant
anyway on a modern kernel as HZ=1000 is simply a precision setting that
affects things like poll()

HZ on a tickless system has no meaningful relationship to wakup rates -
which are what I assume you actually care about.

So do you want to change the precision of poll() and other
functionality ? or do you want to change the wakeup rates and
corresponding virtualisation overhead ?

If the latter then HZ is not the thing to touch.

What are you *actually* trying to achieve ?
What measurements have you done that make you think HZ is relevant in a
tickless kernel ?


Alan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/