Slight modification. The benchmark was limited to 32 bit values,
and tcp_cubic does cube_root(x * K). I modified the benchmark
program to generate these more typical numbers and reran.
Also since numbers are larger just use 64 bit divide on 64 bit cpu.
Original-Bisect
From: Stephen Hemminger [EMAIL PROTECTED]
Date: Thu, 15 Dec 2005 15:36:08 -0800
$ ./croot 1000
Opteron 2.0 Ghz
math 9671505106 1.230814
old 9676503359 1.287217
bisect 9666502089 1.074139
newton 9671507303 1.168087
Xeon (32bit) 2.4 Ghz
math 9671505106 3.047887
old 9676503359
Hi Stephen,
Replace cube root algorithim with a faster version using Newton-Raphson.
Surprisingly, doing the scaled div64_64 is faster than a true 64 bit
division on 64 bit CPU's.
Interesting, what cpu was this on? Was there much difference between the
two methods?
Anton
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Replace cube root algorithim with a faster version using Newton-Raphson.
Surprisingly, doing the scaled div64_64 is faster than a true 64 bit
division on 64 bit CPU's.
Signed-off-by: Stephen Hemminger [EMAIL PROTECTED]
--- net-2.6.16.orig/net/ipv4/tcp_cubic.c
+++ net-2.6.16/net/ipv4/tcp_cubic.c
