Messages in this thread |  | | | Date | Wed, 18 Jul 2012 16:11:03 -0700 | | From | John Stultz <> | | Subject | Re: [PATCH] Allow CLOCK_TICK_RATE to be undefined |
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On 07/18/2012 03:51 PM, Andrew Morton wrote: > On Tue, 17 Jul 2012 17:41:40 +0100 > Catalin Marinas <catalin.marinas@arm.com> wrote: > >> This patch allows an architecture to not define CLOCK_TICK_RATE, in >> which case ACTHZ defaults to (HZ << 8). > No reason was given for this change. > > So those people who are wondering "why don't you just define > CLOCK_TICK_RATE" are made all sad.
I just queued this patch with a revised commit message:
jiffies: Allow CLOCK_TICK_RATE to be undefined
CLOCK_TICK_RATE is a legacy constant that defines the timer device's granularity. On hardware with particularly coarse granularity, this constant is used to reduce accumulated time error when using jiffies as a clocksource, by calculating the hardware's actual tick length rather then just assuming it is 1sec/HZ.
However, for the most part this is unnecessary, as most modern systems don't use jiffies for their clocksource, and their tick device is sufficiently fine grained to avoid major error.
Thus, this patch allows an architecture to not define CLOCK_TICK_RATE, in which case ACTHZ defaults to (HZ << 8).
Let me know if you'd like to see further improvements.
thanks -john
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