Process accounting/timing has broken recently
Julian Elischer
julian at freebsd.org
Mon Dec 6 00:00:36 UTC 2010
On 12/5/10 3:18 PM, Steve Kargl wrote:
> Sometime in the last 7-10 days, some one made a
> change that has broken process accounting/timing.
>
> laptop:kargl[42] foreach i ( 0 1 2 3 4 5 6 7 8 9 )
> foreach? time ./testf
> foreach? end
> Max ULP: 0.501607 for x in [-18.000000:88.709999] with dx = 1.067100e-04
> 69.55 real 38.39 user 30.94 sys
> Max ULP: 0.501607 for x in [-18.000000:88.709999] with dx = 1.067100e-04
> 68.82 real 40.95 user 27.60 sys
> Max ULP: 0.501607 for x in [-18.000000:88.709999] with dx = 1.067100e-04
> 69.14 real 38.90 user 30.02 sys
> Max ULP: 0.501607 for x in [-18.000000:88.709999] with dx = 1.067100e-04
> 68.79 real 40.59 user 27.99 sys
> Max ULP: 0.501607 for x in [-18.000000:88.709999] with dx = 1.067100e-04
> 68.93 real 39.76 user 28.96 sys
> Max ULP: 0.501607 for x in [-18.000000:88.709999] with dx = 1.067100e-04
> 68.71 real 41.21 user 27.29 sys
> Max ULP: 0.501607 for x in [-18.000000:88.709999] with dx = 1.067100e-04
> 69.05 real 39.68 user 29.15 sys
> Max ULP: 0.501607 for x in [-18.000000:88.709999] with dx = 1.067100e-04
> 68.99 real 39.98 user 28.80 sys
> Max ULP: 0.501607 for x in [-18.000000:88.709999] with dx = 1.067100e-04
> 69.02 real 39.64 user 29.16 sys
> Max ULP: 0.501607 for x in [-18.000000:88.709999] with dx = 1.067100e-04
> 69.38 real 37.49 user 31.67 sys
>
> testf is a numerically intensive program that tests the
> accuracy of expf() in a tight loop. User time varies
> by ~3 seconds on my lightly loaded 2 GHz core2 duo processor.
> I'm fairly certain that the code does not suddenly grow/loose
> 6 GFLOP of operations.
>
I know it's a lot to ask but it may be something that you can help
with if you
had the time to triangulate in on the change that did it..
I presume that since you are an "old hand" you can check out sources
at different revisions..
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