Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH] vfs: replace current_kernel_time64 with ktime equivalent | Date | Wed, 20 Jun 2018 09:19:18 -0700 |
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Arnd Bergmann <arnd@arndb.de> writes: > > To clarify: current_kernel_time() uses at most millisecond resolution rather > than microsecond, as tkr_mono.xtime_nsec only gets updated during the > timer tick.
Ah you're right. I remember now: the motivation was to make sure there is basically no overhead. In some setups the full gtod can be rather slow, particularly if it falls back to some crappy timer.
I think it would be ok if it falls back to jiffies if TSC or a similar fast timer doesn't work. But the function you're using likely doesn't do that?
> Has that time scale changed over the past 16 years as CPUs got faster > (and system call entry times slower down again with recent changes)?
Maybe a bit, but not substantially.
-Andi
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