On Monday 18 June 2007 10:12:21 pm Vernon Mauery wrote:
> In looking at the performance characteristics of my network I found that
> 2.6.21.5-rt15 suffers from degraded thoughput with multiple threads. The
> test that I did this with is simply invoking 1, 2, 4, and 8 instances of
> netperf at a time and measuring the total throughput. I have two 4-way
> machines connected with 10GbE cards. I tested several kernels (some older
> and some newer) and found that the only thing in common was that with -RT
> kernels the performance went down with concurrent streams.
I just tested this using lo instead of the 10GbE adapter. I found similar
results. Since this makes it reproducible by just about anybody (maybe the
only factor now is the number of CPUs), I have attached the script that I
test things with.
So with the script run like ./stream_test 127.0.0.1 on 2.6.21 and
2.6.21.5-rt17 I got the following:
2.6.21
=======================
default: 1 streams: Send at 2790.3 Mb/s, Receive at 2790.3 Mb/s
default: 2 streams: Send at 4129.4 Mb/s, Receive at 4128.7 Mb/s
default: 4 streams: Send at 7949.6 Mb/s, Receive at 7735.5 Mb/s
default: 8 streams: Send at 7930.7 Mb/s, Receive at 7910.1 Mb/s
1Msock: 1 streams: Send at 2810.7 Mb/s, Receive at 2810.7 Mb/s
1Msock: 2 streams: Send at 4093.4 Mb/s, Receive at 4092.6 Mb/s
1Msock: 4 streams: Send at 7887.8 Mb/s, Receive at 7880.4 Mb/s
1Msock: 8 streams: Send at 8091.7 Mb/s, Receive at 8082.2 Mb/s
2.6.21.5-rt17
======================
default: 1 streams: Send at 938.2 Mb/s, Receive at 938.2 Mb/s
default: 2 streams: Send at 1476.3 Mb/s, Receive at 1436.9 Mb/s
default: 4 streams: Send at 1489.8 Mb/s, Receive at 1145.0 Mb/s
default: 8 streams: Send at 1099.8 Mb/s, Receive at 1079.1 Mb/s
1Msock: 1 streams: Send at 921.4 Mb/s, Receive at 920.4 Mb/s
1Msock: 2 streams: Send at 1332.2 Mb/s, Receive at 1311.5 Mb/s
1Msock: 4 streams: Send at 1483.0 Mb/s, Receive at 1137.8 Mb/s
1Msock: 8 streams: Send at 1446.2 Mb/s, Receive at 1135.6 Mb/s
--Vernon
> While the test was showing the numbers for receiving as well as sending,
> the receiving numbers are not reliable because that machine was running a
> -RT kernel for these tests.
>
> I was just wondering if anyone had seen this problem before or would have
> any idea on where to start hunting for the solution.
>
> --Vernon
>
> The key for this is 'default' was invoked like:
> netperf -c -C -l 60 -H 10.2.2.4 -t UDP_STREAM -- -m 1472 -M 1472
> and '1Msock' was invoked like:
> netperf -c -C -l 60 -H 10.2.2.4 -t UDP_STREAM -- -m 1472 -M 1472 -s 1M -S
> 1M
>
> 2.6.21
> ==============
> default: 1 streams: Send at 2844.2 Mb/s, Receive at 2840.1 Mb/s
> default: 2 streams: Send at 3927.9 Mb/s, Receive at 3603.9 Mb/s
> default: 4 streams: Send at 4197.4 Mb/s, Receive at 3776.3 Mb/s
> default: 8 streams: Send at 4223.9 Mb/s, Receive at 3848.9 Mb/s
> 1Msock: 1 streams: Send at 4232.3 Mb/s, Receive at 3914.4 Mb/s
> 1Msock: 2 streams: Send at 5428.8 Mb/s, Receive at 3853.2 Mb/s
> 1Msock: 4 streams: Send at 6202.1 Mb/s, Receive at 3774.8 Mb/s
> 1Msock: 8 streams: Send at 6225.1 Mb/s, Receive at 3754.7 Mb/s
>
> 2.6.21.5-rt15
> ===============
> default: 1 streams: Send at 3091.6 Mb/s, Receive at 3048.1 Mb/s
> default: 2 streams: Send at 3768.8 Mb/s, Receive at 3714.2 Mb/s
> default: 4 streams: Send at 1873.6 Mb/s, Receive at 1825.9 Mb/s
> default: 8 streams: Send at 1806.5 Mb/s, Receive at 1792.7 Mb/s
> 1Msock: 1 streams: Send at 3680.4 Mb/s, Receive at 3255.6 Mb/s
> 1Msock: 2 streams: Send at 4129.8 Mb/s, Receive at 3991.5 Mb/s
> 1Msock: 4 streams: Send at 1862.1 Mb/s, Receive at 1787.1 Mb/s
> 1Msock: 8 streams: Send at 1790.2 Mb/s, Receive at 1556.8 Mb/s
#!/bin/sh
# File: stream_test
# Description: test network throughput with a varying number of streams
# Author: Vernon Mauery <[email protected]>
# Copyright: IBM Corporation (C) 2007
instances="1 2 4 8"
msg_size=
time=60
TEST=UDP_STREAM
sock_size=
function usage() {
echo "usage: $0 [-t|-u] [-c N] [-m N] [-s N] [-T N] [-x ...] <target ip addr>"
echo " -t, -u run TCP or UDP tests respectively (default: UDP)"
echo " -c N run N concurrent instances (default \"1 2 4 8\")"
echo " -m N set message size to N bytes (default 1472)"
echo " -s N set socket buffer size (default 1M)"
echo " -T N run test for N seconds (default 60)"
echo " -x '...' pass extra ags to netperf (included after -- )"
echo " -h display this message"
}
while [ $# -gt 0 ]; do
case $1 in
-t)
TEST=TCP_STREAM
;;
-u)
TEST=UDP_STREAM
;;
-c)
shift
instances=$1
;;
-m)
shift
msg_size=$1
;;
-s)
shift
sock_size=$1
;;
-T)
shift
time=$1
;;
-x)
shift
extra_args=$1;
;;
-h)
usage
exit 0
;;
*)
TARGET=$1
;;
esac
shift
done
if [ -z "$TARGET" ]; then
exit 1
fi
if ! ping -c 1 $TARGET >&/dev/null; then
echo "could not connect to $TARGET"
usage
exit 1
fi
if [ -z "$msg_size" ]; then
case $TEST in
TCP_STREAM)
msg_size=256k
;;
UDP_STREAM)
msg_size=1472
;;
esac
fi
if [ -z "$sock_size" ]; then
case $TEST in
TCP_STREAM)
sock_size=2M
;;
UDP_STREAM)
sock_size=1M
;;
esac
fi
function execute() {
ITERS=$1
NAME=$2
ARGS=$3
for ((i=0; i<$ITERS; i++)); do
command="./netperf -c -C -l $time -H $TARGET -t $TEST -- $ARGS $extra_args"
echo $command
echo $command > out.$$.$i
$command >> out.$$.$i &
done
for ((i=1; i<=$ITERS; i++)); do
wait %$i
done
date > results-$NAME.$$.$ITERS
uname -a >> results-$NAME.$$.$ITERS
cat out.$$.* >> results-$NAME.$$.$ITERS
rm -f out.$$.*
}
function parse_TCP_STREAM() {
ITER=$1
NAME=$2
SEND=`( cat results-$NAME.$$.$ITER | grep "^[ 0-9]" | awk '{printf "%s + ", \$5 }'; echo "0 " ) | bc`
echo "** $NAME: $ITER streams: Send at $SEND Mb/s"
}
function parse_UDP_STREAM() {
ITER=$1
NAME=$2
SEND=`( cat results-$NAME.$$.$ITER | grep "^[ 0-9]" | awk 'NR % 2 == 1 {printf "%s + ", \$6 }'; echo "0 " ) | bc`
RECV=`( cat results-$NAME.$$.$ITER | grep "^[ 0-9]" | awk 'NR % 2 == 0 {printf "%s + ", \$4 }'; echo "0 " ) | bc`
echo "** $NAME: $ITER streams: Send at $SEND Mb/s, Receive at $RECV Mb/s"
}
function cleanup() {
for ((i=1; i<=$ITERS; i++)); do
kill -9 %$i
done
rm -f out.$$.*
exit
}
trap cleanup SIGINT SIGQUIT
rm -f out.$$.*
echo "results can be found in results-$$.*"
for C in $instances; do
execute $C default "-m $msg_size -M $msg_size"
parse_$TEST $C default
execute $C ${sock_size}sock "-m $msg_size -M $msg_size -s $sock_size -S $sock_size"
parse_$TEST $C ${sock_size}sock
done
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