Re: dynamic-hz

Andrea Arcangeli
2004-12-14T02:08:08Z

On Mon, Dec 13, 2004 at 09:49:33PM +0100, Pavel Machek wrote:
> Yes, it was supposed to be simple, so that Andrea understands that
> there's nothing inherently broken with single-shot timers.

Single shot timer is unusable for system time accounting, at least as
long as you want to allow nmi. This is a tangible fact, no matter how
simple the example is.

Even the lost tick compensation is not working at all, and it has the
same issues that the one-shot timer has in keeping the system time
accurate.

Pavel, write a program to do iopl(2) cli() wait 3msec; sti() wait 3msec
cli() wait 3msec in a loop. Then watch your system time go in the future
at a rate of a few minutes per hour, then fix it. After you fixed it
we'll get my attention about one-shot timer again ;). I already tried to
fix it and failed so far since I can't see bugs in the current code.
(actually I fixed it by breaking the code, and dropping some ticks
somewhere)