From e0bcd61f92dbfd1fd9b6acc7387ec531449dcbac Mon Sep 17 00:00:00 2001 From: Isaku Yamahata Date: Mon, 1 Apr 2013 11:58:54 +0900 Subject: [PATCH] lib/packet/packet_utils: optimize checksum builtin function, sum, is much faster than for loop. The result on my machine is as follows > def main(): > from timeit import timeit > data = bytearray().zfill(1500) > print 'new=', timeit(lambda : checksum(data), number=1000) > print 'old=', timeit(lambda : checksum_old(data), number=1000) > > new= 0.00800108909607 > old= 0.266770124435 Signed-off-by: Isaku Yamahata Signed-off-by: FUJITA Tomonori --- ryu/lib/packet/packet_utils.py | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/ryu/lib/packet/packet_utils.py b/ryu/lib/packet/packet_utils.py index b8f2e058..c36be490 100644 --- a/ryu/lib/packet/packet_utils.py +++ b/ryu/lib/packet/packet_utils.py @@ -13,6 +13,7 @@ # See the License for the specific language governing permissions and # limitations under the License. +import array import socket import struct @@ -26,10 +27,10 @@ def checksum(data): if len(data) % 2: data += '\x00' - s = 0 - for i in range(0, len(data), 2): - w = data[i] + (data[i + 1] << 8) - s = carry_around_add(s, w) + data = str(data) # input can be bytearray. + s = sum(array.array('H', data)) + s = (s & 0xffff) + (s >> 16) + s += (s >> 16) return socket.ntohs(~s & 0xffff)