Bandwidth testing

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Revision as of 18:38, 14 May 2010 by Hiram (talk | contribs) (clarify procedures and multiple copies)
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Units

For these measurements:

  • 1 kB/s = 1,000 bytes per second
  • 1 mB/s = 1,000,000 bytes per second
  • 1 gB/s = 1,000,000,000 bytes per second

Memory:

  • 1 Kb = 1024^2 bytes = 1,048,576 bytes
  • 1 Gb = 1024^3 bytes = 1,073,741,824 bytes
  • 1 Tb = 1024^4 bytes = 1,099,511,627,776 bytes

Machines tested

machine
name
processor
speed
memSize10 files
of size
dd /dev/zero
to /dev/shm
cp /dev/shm
to /tmp
cp /dev/shm
to hive
rsync /dev/shm
to /dev/shm
rsync /dev/shm
via rsh
UDT via
UPD
hgwdevOpteron
1150 Mhz
32 Gb1 gB5278 mB/s
10X dd
287 mB/s58 mB/s1638 mB/s
20X rsync
n/a4070 mB/s
10X send
kolossusIntel
2261 Mhz
1 Tb1 gB6700 mB/s
10X dd
192 mB/s58 mB/s120 mB/s
4X rsync
115 mB/s1135 mB/s
okazakiIntel
1600 Mhz
2 Gb75 mB700 mB/s90 mB/s11.3 mB/s11.5 mB/s11.6 mB/s10.7 mB/s
4X send
mitzieIntel
400 Mhz
512 Kb18 mB113 mB/s25 mB/sn/a54.4 kB/s up
316 kB/s down
n/a
cloud0Opteron
2000 Mhz
7.5 Gb288 mB940 mB/s
4X dd
78 mB/sn/a16 mB/s
2X rsync
43 mB/s
3X rsync
46 mB/s
3X send

Procedure

Sizing files based on available /dev/shm space. Largest file size limited to 1 gB.

The /dev/zero to /dev/shm write is done a dd command:

 dd if=/dev/zero of=/dev/shm/memToMem.$I.zero bs=200000 count=$ddCount

Running multiple copies of that simultaneously until the best speed was obtained.

The /dev/shm copy to /tmp is done the cp command:

cp -p /dev/shm/memToMem.$I.zero ./memToFile.$I.zero

Running multiple copies of that simultaneously until the best speed was obtained. It only took several (2 to 3) multiple instances before they began to interfere with each other and slow down the effective rate.

The /dev/shm copy to the hive filesystem was done with the cp command:

cp -p /dev/shm/memToMem.$I.zero ./memToFile.$I.zero

Running multiple copies of that simultaneously did not improve the speed on the machine where the copies were running. However, running copies from multiple machines at the same time to the same hive directory did not interfere with each other. They were independent of the other activity.

The rsync /dev/shm to /dev/shm was to and from hgwdev. Multiple instances of rsync from kolossus to hgwdev seemed to add together for a total bandwidth higher than a single instance of rsync.

The machine mitzie is at the end of a Santa Cruz DSL line and over a WiFi network connection across the driveway to the garage. The WiFi link is faster than the DSL line.