Re: dynamic-hz

john stultz
2004-12-13T20:58:29Z

On Sat, 2004-12-11 at 06:23, Andrea Arcangeli wrote:
> This patch is quite intrusive since many HZ visible to userspace have to
> be converted to USER_HZ, and most important because HZ isn't available
> at compile time anymore and every variable in function of HZ must be
> either changed to be in function of USER_HZ or it must be initialized at
> runtime. The code has debugging code (optional at compile time) so that
> I can guarantee that there cannot be any regression.

Interesting patch, I know some folks have been asking about HZ=10k
recently, so this could help.

The only bit that worries me a bit is the change from HZ->USER_HZ for
internal calculations. In my mind, USER_HZ should only be used for
converting internal system ticks to userspace-visible ticks. Changing
drivers to think about things in user-ticks confuses things a bit since
suddenly some kernel code is thinking in user-ticks and others in
system-ticks. It just muddles things a bit.

thanks
-john