Process accounting/timing has broken recently
Julian Elischer
julian at freebsd.org
Mon Dec 6 06:22:38 UTC 2010
On 12/5/10 10:19 PM, Garrett Cooper wrote:
> On Sun, Dec 5, 2010 at 10:12 PM, Steve Kargl
> <sgk at troutmask.apl.washington.edu> wrote:
>> On Sun, Dec 05, 2010 at 04:00:32PM -0800, Julian Elischer wrote:
>>> 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..
>> I was hoping that someone (possibly the person responsible) would
>> recognize the symptoms and recommend a revision or two to revert.
>> Otherwise, doing a binary search will take some time in that it
>> takes 4+ hours for a buildworld/kernel cycle on my laptop.
> If you can provide the source for the application you're running
> above and instructions on how to compile it, I can at least give you a
> bit of a head start :).
> Thanks,
> -Garrett
>
plus which probably just
`cd /sys/amd64/conf config GENERIC;cd ../compile/GENERIC; make
kernel` would be enough...
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