Messages in this thread | | | Date | Fri, 15 Jul 2005 15:12:51 +0200 | From | Jesper Juhl <> | Subject | Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt |
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On 7/15/05, Linus Torvalds <torvalds@osdl.org> wrote: > > On Fri, 15 Jul 2005, Jesper Juhl wrote: > > > > It's buggy, that I know. setting kernel_hz (the new boot parameter) to > > 250 causes my system clock to run at something like 4-5 times normal > > speed > > 4 times normal. You don't actually make the timer interrupt happen at > 250Hz, so the timer will be programmed to run at the full 1kHz. > Right, that's the basic problem. I increase jiffies at a higher rate but didn't slow the timer interrupt down at the same time.
> You also need to actually change the LATCH define (in > include/linux/jiffies.h) to take this into account (there might be > something else too). > [...] > and you might be getting closer. > > Of course, you need to make sure that LATCH is used only after > jiffies_increment is set up. See "setup_pit_timer(void)" in > arch/i386/kernel/timers/timer_pit.c for more details. >
Thank you for all the pointers and hints. This is a new area of code for me, so I'll need some time to poke around - the above helps a lot. Unfortunately I won't have any time to work on this today, but I'll see if I can get a working implementation together tomorrow.
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