[Python-Dev] Speed of test_sort.py
Thu, 01 Aug 2002 14:11:42 -0400
[Guido, mixing test_longexp w/ the new test_sort]
> It's about the same on my Linux box (system time is CPU time spent in
> the kernel):
Dang! I was more than half hoping it was a Windows glitch.
> test_longexp alone takes 1.92 user + 0.22 system seconds.
> test_sort alone takes 1.71 user + 0.01 system seconds.
> test_sort + test_longexp takes 3.62 user + 0.18 system seconds.
> test_longexp + test_sort takes 38.05 user and 0.34 system seconds!!!
> I'll see if I can get this to run under a profiler.
It's intriguing, but I have to do other things today. Here's a
self-contained test case that allows to vary REPS from the command line:
from time import clock as now
l = eval("[" + "2," * REPS + "]")
assert len(l) == REPS
x.sort(lambda x, y: cmp(x, y))
# Doing x.sort(cmp) instead, there's no slowdown, so it's not just
# that there's an explicit comparison function.
x = range(1000)
REPS = 65580
if len(sys.argv) > 1:
REPS = int(sys.argv)
t1 = now()
t2 = now()
t3 = now()
print "At REPS=%d, longexp %.2g sort %.2g" % (REPS, t2-t1, t3-t2)
On my box, the time it takes for the sort appears, after a certain point, to
grow quadratically(!) in the REPS value (these timings were hasty and not on
a quiet box, so only gross conclusions are justified):
C:\Code\python\PCbuild>python temp.py 1
At REPS=1, longexp 0.00021 sort 0.027
At REPS=1, longexp 0.00018 sort 0.036
At REPS=10, longexp 0.00035 sort 0.053
At REPS=100, longexp 0.002 sort 0.028
At REPS=1000, longexp 0.039 sort 0.073
At REPS=10000, longexp 0.47 sort 0.45
At REPS=20000, longexp 0.89 sort 0.44
At REPS=40000, longexp 1.5 sort 1.3
At REPS=80000, longexp 2.5 sort 5.9
At REPS=160000, longexp 5 sort 22