Messages in this thread Patch in this message | | | Date | Sun, 05 Mar 2006 02:15:42 +0900 (JST) | Subject | Re: [PATCH] simplify update_times (avoid jiffies/jiffies_64 aliasing problem) | From | Atsushi Nemoto <> |
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>>>>> On Fri, 03 Mar 2006 12:17:28 -0800, john stultz <johnstul@us.ibm.com> said:
john> I'm not opposed to queuing it up as it seems like a logical john> cleanup. I'd be fine with it going in before my patch, however john> it still needs to address i386 lost tick compensation. I worry john> that addressing that issue before my patchset (which makes the john> lost tick compensation unnecessary) might be a bit more john> complex. I think it would be easier going in after my patch. I john> do think the barrier fix (with a comment) is a good short term john> fix.
john> Atsushi: Your thoughts?
I agree. I missed i386 lost tick case and it seems more complex than x86_64 case. Your patchset looks to make this cleanup very easy. Then, here is an updated barrier fix patch.
Add an optimization barrier to prevent prefetching jiffies before incrementing jiffies_64.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
diff --git a/kernel/timer.c b/kernel/timer.c index fc6646f..decd19e 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -925,6 +925,8 @@ static inline void update_times(void) void do_timer(struct pt_regs *regs) { jiffies_64++; + /* prevent loading jiffies before storing new jiffies_64 value. */ + barrier(); update_times(); softlockup_tick(regs); } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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