Clock fuzzing bugs

[Richard Laager]

On 11/24/19 3:41 AM, Hal Murray via devel wrote:
> rlaager at wiktel.com said:
>> I can build from git or with whatever patches, if needed. If something is
>> wrong with this clock fuzzing code, I'd love to help get to the bottom of it,
>> but this doesn't seem like the sort of thing I can sort out by myself. 
> 
> I don't have any good ideas.
> 
> Can you try running with ntpd locked to a particular CPU?

No change.

> There is another clock toy in ntpsec/attic/clocks.c

rlaager at ntp2:~$ ./a.out
      res   avg      min  dups  CLOCK
        1    31       29        CLOCK_REALTIME
  4000000     9  3999945    -4  CLOCK_REALTIME_COARSE
        1    30       26        CLOCK_MONOTONIC
        1   380      366        CLOCK_MONOTONIC_RAW
        1   389      374        CLOCK_BOOTTIME
Found faster: 29 => -3

Histogram: CLOCK_REALTIME, 1 ns per bucket, 1000000 samples.
        ns      hits
        26     49938
        27    531902
        28     49731
        29       117
        30    368271
        36         1
        39         1
        51         1
        57         1
        69         1
36 samples were bigger than 69.
rlaager at ntp2:~$ ./a.out
      res   avg      min  dups  CLOCK
        1    28       26        CLOCK_REALTIME
  4000000     8  3999946    -1  CLOCK_REALTIME_COARSE
        1    28       24        CLOCK_MONOTONIC
        1   380      368        CLOCK_MONOTONIC_RAW
        1   390      374        CLOCK_BOOTTIME

Histogram: CLOCK_REALTIME, 1 ns per bucket, 1000000 samples.
        ns      hits
        26     49229
        27    523381
        28     48989
        29       153
        30    378207
        32         1
        33         1
        36         3
        39         1
        56         1
34 samples were bigger than 56.
rlaager at ntp2:~$ ./a.out
      res   avg      min  dups  CLOCK
        1    28       26        CLOCK_REALTIME
  4000000     8  3999945    -1  CLOCK_REALTIME_COARSE
        1    28       24        CLOCK_MONOTONIC
        1   377      366        CLOCK_MONOTONIC_RAW
        1   389      377        CLOCK_BOOTTIME

Histogram: CLOCK_REALTIME, 1 ns per bucket, 1000000 samples.
        ns      hits
        26     49233
        27    523451
        28     48993
        29       163
        30    378123
        33         2
        36         1
        39         1
        42         1
        45         1
31 samples were bigger than 45.

-- 
Richard

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