Created
December 11, 2011 11:36
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Simulation of rt_garbage_collect()
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# -*- coding: utf-8 -*- | |
""" | |
Simulate route cache with the following assumptions: | |
1. route cache is never full (things become difficult in this case) | |
2. route cache is always able to meet its goal (check gc_goal_miss | |
counter to see if this is your case) | |
""" | |
from matplotlib.pylab import * | |
import random | |
# Compute various data | |
def entries(route, seconds, max_size, rhash_entries, | |
gc_min_interval, gc_elasticity, gc_thresh): | |
""" | |
`route` is a function taking two arguments: time in seconds and | |
number of entries. This allows to specify the number of new route | |
at the given second. | |
`seconds` is the number of seconds to run. | |
""" | |
time = np.arange(0, seconds, gc_min_interval) | |
routes = np.zeros(len(time)) | |
entries = np.zeros(len(time)) | |
goal = np.zeros(len(time)) | |
equilibrium = np.zeros(len(time)) | |
for i in xrange(1, len(time)): | |
entries1 = entries[i-1] | |
routes1 = route(time[i], entries1) | |
if entries1 < gc_thresh: | |
# No garbage collector | |
entries[i] = entries1 + routes1 | |
goal[i] = goal[i-1] | |
equilibrium[i] = equilibrium[i-1] | |
continue | |
# Garbage collector | |
# See net/ipv4/route.c (rt_garbage_collect) | |
goal1 = entries[i-1] - gc_elasticity*rhash_entries | |
if goal1 <= 0: | |
eq1 = max(equilibrium[i-1], gc_thresh) | |
goal1 = entries[i-1] - eq1 | |
if goal1 > 0: | |
eq1 = eq1 + min(goal1/2, rhash_entries) | |
goal1 = entries[i] | |
else: | |
goal1 = max(goal1/2, rhash_entries) | |
eq1 = entries1 - goal1 | |
if goal1 < 0: | |
eq1 = eq1 + goal1 | |
# We assume here that we are able to meet our goal | |
entries[i] = min(entries1 + routes1 - max(0, goal1), | |
max_size) | |
goal[i] = goal1 | |
equilibrium[i] = eq1 | |
routes[i] = routes1 | |
return time, entries | |
# Setup axis | |
rcParams['font.size'] = 11 | |
rcParams['legend.loc'] = 'best' | |
fig = figure(num=None, figsize=(11.69, 8.27), dpi=100) | |
lines = [] | |
def route2(t, e): | |
if t < 1000: | |
return 1000-e/6000 | |
if t < 2000: | |
return 100000 | |
return 1000-e/6000 | |
t, e = entries(route2, seconds=3000, | |
max_size=2**22, rhash_entries=2**18, | |
gc_min_interval=0.5, gc_elasticity=8, gc_thresh=2**18) | |
lines.append(plot(t, e, ':', color="#E97F02", | |
label="Attack ~100 000/s, 262144..4194304, t=262144, e=8")) | |
def route3(t, e): | |
if t < 1000: | |
return 1000-e/6000 | |
if t < 2000: | |
return 0 | |
return 1000-e/6000 | |
t, e = entries(route3, seconds=3000, | |
max_size=2**22, rhash_entries=2**18, | |
gc_min_interval=0.5, gc_elasticity=8, gc_thresh=2**18) | |
lines.append(plot(t, e, '-', color="#8A9B0F", | |
label="Paused, 262144..4194304, t=262144, e=8")) | |
route1 = lambda t,e: 1000-e/6000 | |
t, e = entries(route1, seconds=3000, | |
max_size=2**22, rhash_entries=2**18, | |
gc_min_interval=0.5, gc_elasticity=8, gc_thresh=2**18) | |
lines.append(plot(t, e, '-', color="#490A3D", linewidth=2, | |
label="~2000 r/s, 262144..4194304, t=262144, e=8")) | |
t, e = entries(route1, seconds=3000, | |
max_size=2**22, rhash_entries=2**20, | |
gc_min_interval=0.5, gc_elasticity=2, gc_thresh=2**18) | |
lines.append(plot(t, e, '-', color="#BD1550", | |
label="~2000 r/s, 1048576..4194304, t=262144, e=2")) | |
grid(True, which="both", linestyle="dotted", color="gray") | |
xlabel("Elapsed time (s)") | |
legend(fancybox=True, shadow=True, | |
prop=dict(size=10)) | |
#savefig("%s.pdf" % title) | |
#savefig("%s.svg" % title, transparent=True) | |
show() |
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