September 9th, 2010
I'm sitting in class frustrated as could be. The Internet in this room is unbelievably annoying. For some reason, everything runs fine, then functionality drops to unusable levels. Downloading files (i.e., PDFs of lectures) occurs at about 0.5kb/s (wow), and Internet browsing is hopeless. At most, I can connect to IRC and enjoy myself in #electronics, #python, and #linux. I decided to channel my frustration into productivity, and wrote a quick Python script to let me visualize the problem.
Notice the massive lag spikes around the time class begins. I think it's caused by the retarded behavior of windows update and anti-virus software updates being downloaded on a gazillion computers all at the same time which are required to connect to the network on Windows machines. Class start times were 8:30am, 9:35am, and 10:40am. Let's view it on a logarithmic scale:
Finally, the code. It's two scripts:
This script pings a website (kernel.org) every few seconds and records the ping time to "pings.txt":
import socket import time import os import sys import re def getping(): pingaling = os.popen("ping -q -c2 kernel.org") sys.stdout.flush() while 1: line = pingaling.readline() if not line: break line = line.split("n") for part in line: if "rtt" in part: part = part.split(" = ") part = part.split('/') print part+"ms" return part def add2log(stuff): f = open("pings.txt", 'a') f.write(stuff+",") f.close() while 1: print "pinging...", stuff = "[%s,%s]" % (time.time(), getping()) print stuff add2log(stuff) time.sleep(1)
This script graphs the results:
import pylab import time import datetime import numpy def smoothTriangle(data, degree, dropVals=False): triangle = numpy.array(range(degree)+[degree]+range(degree)[::-1])+1 smoothed =  for i in range(degree, len(data)-degree*2): point = data[i:i+len(triangle)]*triangle smoothed.append(sum(point)/sum(triangle)) if dropVals: print "smoothlen:", len(smoothed) return smoothed while len(smoothed) < len(data): smoothed = [None]+smoothed+[None] if len(smoothed) > len(data): smoothed.pop(-1) return smoothed print "reading" f = open("pings.txt") raw = eval("[%s]" % f.read()) f.close() xs, ys, big = , ,  for item in raw: t = datetime.datetime.fromtimestamp(item) maxping = 20000 if item > maxping or item == None: item = maxping big.append(t) ys.append(float(item)) xs.append(t) print "plotting" fig = pylab.figure(figsize=(10, 7)) pylab.plot(xs, ys, 'k.', alpha=.1) pylab.plot(xs, ys, 'k-', alpha=.1) pylab.plot(xs, smoothTriangle(ys, 15), 'b-') pylab.grid(alpha=.3) pylab.axis([None, None, None, 2000]) pylab.ylabel("latency (ping kernel.org, ms)") pylab.title("D3-3 Network Responsiveness") fig.autofmt_xdate() pylab.savefig('out.png') pylab.semilogy() pylab.savefig('out2.png') fig.autofmt_xdate() print "done"