Messages in this thread | | | Date | Fri, 03 Mar 2006 01:07:54 +0900 (JST) | Subject | Re: why do we have wall_jiffies? | From | Atsushi Nemoto <> |
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Oh, I missed this thread...
>>>>> On Fri, 17 Feb 2006 10:46:53 -0800, john stultz <johnstul@us.ibm.com> said: >> In other places there is code that uses (jiffies - wall_jiffies). >> However I can't see any way that jiffies and wall_jiffies could >> ever be different (except for a few nanoseconds while executing the >> code above). I also can't see any way that `ticks' could ever be >> anything other than 1. >> >> Is the wall_jiffies stuff just a leftover from days when we used to >> do timekeeping from a softirq? Or am I missing something >> fundamental?
john> Its only use right now is that on some arches we increment john> jiffies when we detect lost ticks. This then forces xtime to be john> updated the appropriate number of times.
Currently, jiffies and wall_jiffies is _really_ different most of time. The jiffies is almost always one bigger than wall_jiffies (at least on i386 and MIPS). Please refer my yesterday's mail (subject: jiffies_64 vs. jiffies) for the reason.
john> It probably could be killed and the arches can just call john> do_timer() the appropriate number of times. That might clean john> some things up. My TOD work would also make it unnecessary.
I just posted a patch to doing this (subject: [PATCH] simplify update_times ...). I thought only x86_64 is doing such thing, right?
Also, I suppose then we can get rid of wall_jiffies completely. --- Atsushi Nemoto - 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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