"hwclock -w" takes 24 seconds

[Rob Landley]

On Tuesday 13 April 2010 10:08:56 Kim B. Heino wrote:
> BusyBox 1.16.1 on a small armv4tl system:
>
> $ time hwclock -w
> real    0m 24.34s
> user    0m 0.00s
> sys     0m 0.00s
>
> $ time hwclock -w
> real    0m 24.07s
> user    0m 0.01s
> sys     0m 0.00s
>
> $ time hwclock -w
> real    0m 24.20s
> user    0m 0.00s
> sys     0m 0.00s
>
> rem_usec seems to be about 996600 after every iteration. Changing sync
> resolution from 1ms to 5ms helps, but there has to be better solution.
> Denys?

I can confirm this on my armv4tl system image:

  wget http://impactlinux/com/fwl/downloads/binaries/system-image-armv4tl.tar.bz2
  tar xvjf system-image-armv4tl.tar.bz2
  cd system-image-armv4tl
  ./run-emulator.sh

wait through the boot messages...

  (armv4tl) /home # time hwclock -w
  real        0m 24.98s
  user       0m 0.01s
  sys         0m 0.01s

This assumes you have qemu 0.12.x installed.

Rob

P.S: As expected, application emulation is useless here:

  $ qemu-arm ./hwclock
  Unsupported ioctl: cmd=0xffffffff80247009
  hwclock: RTC_RD_TIME: Function not implemented
-- 
Latency is more important than throughput. It's that simple. - Linus Torvalds