Clockrate is based off of my device_polling setup, which is configured
to 4000. burst_max has a hard limit, can't go higher than it already is
at 1000
Could I get an explanation as to what the queue and isr sysctl values
are actually doing? I'll be able to run some more basic tests tomorrow
to see some results, but want to wrap my head around what's actually
logically meant to be happening based on adjustments, etc. [I suspect
this'll do nothing for the UDP issue, but at least I might be able to
pipe some TCP traffic]
[EMAIL PROTECTED] wrote:
Hi,
I think you can try to check/tuning this sysctl variables and the isr
related variables:
net.inet.ip.intr_queue_maxlen
net.inet.ip.intr_queue_drops
net.isr.enable ... try to set
net.isr.directed
net.isr.queued
net.isr.drop
and polling configuration:
kern.clockrate
kern.polling.burst_max
.... increase for high rate of small packets on GE
....
Alessandro
Date: Wed, 07 Feb 2007 01:37:00 -0800
From: Justin Robertson <[EMAIL PROTECTED]>
Subject: 6.x, 4.x ipfw/dummynet pf/altq - network performance issues
To: freebsd-performance@freebsd.org
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
It was suggested I post this to freebsd-performance, it's already in
questions, isp, and net.
I've been running some tests with using FreeBSD to filter and rate limit
traffic. My first thoughts were to goto the latest stable release, which
was 6.1 at the time. I've since done the same test under 6.2 and haven't
seen any difference. I later migrated to running 4.11 to get away from
these issues, but have discovered others.
I've tested on an AMD 3200+ system with dual Intel 1000 series NICs, an
AMD Opteron 165 with the same, and a Xeon 2.8 with the same. I've used
both stock and intel drivers.
6.x;
Normal traffic isn't a problem. The second you get into the realm of
abusive traffic, such a DoS/DDoS (over 100mbps) UDP floods the machine
falls over. Little packets with ip lengths of 28-29 bytes seem to do the
most damage. I've tried playing with various sysctl values and have seen
no difference at all. By "falls over" I mean "stops sending all traffic
in any direction". TCP syn packets have the same effect, tho not quite
as rapidly (200~230mbps). I then tried moving filtering off to a
transparent bridge. This improved the situation somewhat, but an extra
30-40mbps of UDP data and it would ultimately crumble. Overall the
machine would be able to move between 300k-600k PPS before becoming a
cripple, depending on packet length, protocol, and any flags. Without a
specific pf or ipfw rule to deal with a packet the box would fall over,
with specific block rules it would manage an extra 30-40mbps and then
fall over.
4.11;
Again, normal traffic isn't a problem. When routing & filtering on the
same system some of the problems found in 6.x are still apparent, but to
a lesser degree. Splitting the task into a transparent filtering bridge
with a separate routing box appears to clear it up entirely. UDP floods
are much better handled - an ipfw block rule for the packet type and the
machine responds as if there were no flood at all (until total bandwidth
saturation or PPS limits of the hardware, which in this case was around
950Mbps). TCP syn attacks are also better handled, again a block rule
makes it seem as if there were no attack at all. The system also appears
to be able to move 800-900k PPS of any one protocol at a time. However,
the second you try and queue abusive traffic the machine will fall over.
Inbound floods appear to cause ALL inbound traffic to lag horrifically
(while rate limiting/piping), which inherently causes a lot of outbound
loss due to broken TCP. Now, I'm not sure if this is something to do
with dummynet being horribly inefficient, or if there's some sysctl
value to deal with inbound that I'm missing.
I suppose my concerns are two-fold. Why is 6.x collapsing under traffic
that 4.11 could easily block and run merrily along with, and is there a
queueing mechanism in place that doesn't tie up the box so much on
inbound flows that it ignores all other relevant traffic?
(as a note, all tests were done with device polling enabled. Without it
systems fall over pretty quickly. I also tried tests using 3com cards
and had the same results)
In the event anybody is looking for basic errors, device polling is
enabled and running at 4000 hz, which has proved to net the highest
thruput in PPS. ADAPTIVE_GIANT is on (tests resulted in better pps
thruput), all the other monitoring features are disabled, and here are
my sysctl modifications related to networking (if there's something
glaring let me know!);
kern.polling.enable=1
kern.polling.burst_max=1000
kern.polling.each_burst=80
kern.polling.idle_poll=1
kern.polling.user_frac=20
kern.polling.reg_frac=50
net.inet.tcp.recvspace=262144
net.inet.tcp.sendspace=262144
kern.ipc.maxsockbuf=1048576
net.inet.tcp.always_keepalive=1
net.inet.ip.portrange.first=10000
kern.ipc.somaxconn=65535
net.inet.tcp.blackhole=2
net.inet.udp.blackhole=1
net.inet.icmp.icmplim=30
net.inet.ip.forwarding=1
net.inet.ip.portrange.randomized=0
net.inet.udp.checksum=0
net.inet.udp.recvspace=8192 (I've tried large and small, thinking
perhaps I was fulling up buffers on udp floods and then causing it to
drop tcp, there appears to be no difference)
net.inet.ip.intr_queue_maxlen=512
net.inet.tcp.delayed_ack=0
net.inet.tcp.rfc1323=1
net.inet.tcp.newreno=0 (I'd try this, but, the biggest problem is still
with UDP, and I'd prefer something compatible with everything for now)
net.inet.tcp.delacktime=10
net.inet.tcp.msl=2500
net.inet.ip.rtmaxcache=1024
net.inet.raw.recvspace=262144
net.inet.ip.dummynet.hash_size=512
net.inet.ip.fw.dyn_ack_lifetime=30
net.inet.ip.fw.dyn_syn_lifetime=10
net.inet.ip.fw.dyn_fin_lifetime=10
net.inet.ip.fw.dyn_max=16192
net.link.ether.bridge.enable=0 (or 1 on when setup to bridge, obviously)
net.inet.ip.fastforwarding=1
It has also been pointed out that using net.link.ether.ipfw=1 should
negate the need for a transparent box, however the performance disparity
between 6.x and 4.11 remains.
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