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<div class="moz-cite-prefix">On 05/02/2014 03:00 PM, jjs -
mainphrame wrote:<br>
</div>
<blockquote
cite="mid:CABkzw7xATb6SAFq=hVR_0vNzsKvubU6XKDmP__+ds0LLsm4JZg@mail.gmail.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
<div dir="ltr">Just for kicks, here are the data from the tests.
(these were run on a rather modest old machine)
<div><br>
</div>
<div><img src="cid:part1.00010605.04030601@openvz.org"
width="563" height="429.9113530326594"></div>
<div><br>
</div>
<div><br>
</div>
<div>Here are the raw dbench data:</div>
<div><br>
</div>
<div><br>
</div>
<div>
<div><font face="courier new, monospace">#clients
vzhost simfs CT ploop CT</font></div>
<div><font face="courier new, monospace">---------------------------------------------------------------------</font></div>
<div><font face="courier new, monospace">1
11.1297MB/sec 9.96657MB/sec 19.7214MB/sec</font></div>
<div><font face="courier new, monospace">2
12.2936MB/sec 14.3138MB/sec 23.5628MB/sec</font></div>
<div><font face="courier new, monospace">4
17.8909MB/sec 16.0859MB/sec 45.1936MB/sec</font></div>
<div><font face="courier new, monospace">8
25.8332MB/sec 22.9195MB/sec 84.2607MB/sec</font></div>
<div><font face="courier new, monospace">16
32.1436MB/sec 28.921MB/sec 155.207MB/sec</font></div>
<div><font face="courier new, monospace">32
35.5809MB/sec 32.1429MB/sec 206.571MB/sec</font></div>
<div><font face="courier new, monospace">64
34.3609MB/sec 29.9307MB/sec 221.119MB/sec</font></div>
</div>
</div>
</blockquote>
<br>
Well, I can't explain this, but there's probably something wrong
with the test.<br>
<br>
<blockquote
cite="mid:CABkzw7xATb6SAFq=hVR_0vNzsKvubU6XKDmP__+ds0LLsm4JZg@mail.gmail.com"
type="cite">
<div dir="ltr">
<div>
<div><br>
</div>
<div>Here is the script used to invoke dbench:</div>
<div><br>
</div>
<div>
<div><font face="courier new, monospace">HOST=`uname -n`</font></div>
<div><font face="courier new, monospace">WD=/tmp</font></div>
<div>
<font face="courier new, monospace">FILE=/usr/share/dbench/client.txt</font></div>
<div><font face="courier new, monospace"><br>
</font></div>
<div><font face="courier new, monospace">for i in 1 2 4 8 16
32 64</font></div>
<div>
<font face="courier new, monospace">do</font></div>
<div><font face="courier new, monospace"> dbench -D $WD
-c $FILE $i &>dbench-${HOST}-${i}</font></div>
<div><font face="courier new, monospace">done</font></div>
</div>
<div><br>
</div>
<div>Here are the dd commands and outputs:</div>
<div><br>
</div>
<div>
<div><font face="courier new, monospace">OPENVZ HOST</font></div>
<div><font face="courier new, monospace">----------------</font></div>
<div><font face="courier new, monospace">[root@vzhost ~]# dd
bs=1M count=512 if=/dev/zero of=test conv=fdatasync</font></div>
<div><font face="courier new, monospace">512+0 records in</font></div>
<div><font face="courier new, monospace">512+0 records out</font></div>
<div><font face="courier new, monospace">536870912 bytes
(537 MB) copied, 11.813 s, 45.4 MB/s</font></div>
<div><font face="courier new, monospace">[root@vzhost ~]# df
-T</font></div>
<div><font face="courier new, monospace">Filesystem Type
1K-blocks Used Available Use% Mounted on</font></div>
<div><font face="courier new, monospace">/dev/sda2 ext4
20642428 2390620 17203232 13% /</font></div>
<div><font face="courier new, monospace">tmpfs
tmpfs 952008 0 952008 0% /dev/shm</font></div>
<div><font face="courier new, monospace">/dev/sda1 ext2
482922 68436 389552 15% /boot</font></div>
<div><font face="courier new, monospace">/dev/sda4 ext4
51633780 3631524 45379332 8% /local</font></div>
<div><font face="courier new, monospace">[root@vzhost ~]# </font></div>
<div><font face="courier new, monospace"><br>
</font></div>
<div><font face="courier new, monospace"><br>
</font></div>
<div><font face="courier new, monospace">PLOOP CT</font></div>
<div><font face="courier new, monospace">----------------</font></div>
<div><font face="courier new, monospace">root@vz101:~# dd
bs=1M count=512 if=/dev/zero of=test conv=fdatasync</font></div>
<div><font face="courier new, monospace">512+0 records in</font></div>
<div><font face="courier new, monospace">512+0 records out</font></div>
<div><font face="courier new, monospace">536870912 bytes
(537 MB) copied, 2.50071 s, 215 MB/s</font></div>
</div>
</div>
</div>
</blockquote>
<br>
This one I can explain :)<br>
<br>
This is caused by ploop optimization that was enabled in the kernel
recently.<br>
If data block is all zeroes, it is not written to the disk (same
thing as sparse files,<br>
just for ploop).<br>
<br>
So you need to test it with some real data (anything but not all
zeroes).<br>
I am not sure how fast is /dev/urandom but this is one of the
options.<br>
<br>
<blockquote
cite="mid:CABkzw7xATb6SAFq=hVR_0vNzsKvubU6XKDmP__+ds0LLsm4JZg@mail.gmail.com"
type="cite">
<div dir="ltr">
<div>
<div>
<div><font face="courier new, monospace"><br>
</font></div>
<div><font face="courier new, monospace">root@vz101:~# df -T</font></div>
<div><font face="courier new, monospace">Filesystem
Type 1K-blocks Used Available Use% Mounted on</font></div>
<div><font face="courier new, monospace">/dev/ploop11054p1
ext4 4539600 1529316 2804928 36% /</font></div>
<div><font face="courier new, monospace">none
devtmpfs 262144 4 262140 1% /dev</font></div>
<div><font face="courier new, monospace">none
tmpfs 52432 52 52380 1% /run</font></div>
<div><font face="courier new, monospace">none
tmpfs 5120 0 5120 0% /run/lock</font></div>
<div><font face="courier new, monospace">none
tmpfs 262144 0 262144 0% /run/shm</font></div>
<div><font face="courier new, monospace">root@vz101:~#</font></div>
<div><font face="courier new, monospace"><br>
</font></div>
<div><font face="courier new, monospace"><br>
</font></div>
<div><font face="courier new, monospace">SIMFS CT</font></div>
<div><font face="courier new, monospace">----------------</font></div>
<div><font face="courier new, monospace">root@vz102:~# dd
bs=1M count=512 if=/dev/zero of=test conv=fdatasync</font></div>
<div><font face="courier new, monospace">512+0 records in</font></div>
<div><font face="courier new, monospace">512+0 records out</font></div>
<div><font face="courier new, monospace">536870912 bytes
(537 MB) copied, 12.6913 s, 42.3 MB/s</font></div>
<div><font face="courier new, monospace">root@vz102:~# df -T</font></div>
<div><font face="courier new, monospace">Filesystem Type
1K-blocks Used Available Use% Mounted on</font></div>
<div><font face="courier new, monospace">/dev/simfs
simfs 4194304 1365500 2828804 33% /</font></div>
<div><font face="courier new, monospace">none
devtmpfs 262144 4 262140 1% /dev</font></div>
<div><font face="courier new, monospace">none
tmpfs 52432 52 52380 1% /run</font></div>
<div><font face="courier new, monospace">none
tmpfs 5120 0 5120 0% /run/lock</font></div>
<div><font face="courier new, monospace">none
tmpfs 262144 0 262144 0% /run/shm</font></div>
<div><font face="courier new, monospace">root@vz102:~# </font></div>
</div>
<div><font face="courier new, monospace"><br>
</font></div>
<div><font face="arial, helvetica, sans-serif">Regards,</font></div>
<div><font face="arial, helvetica, sans-serif"><br>
</font></div>
<div><font face="arial, helvetica, sans-serif">J J</font></div>
<div><font face="arial, helvetica, sans-serif"><br>
</font></div>
<font face="arial, helvetica, sans-serif">​</font><br>
</div>
</div>
<div class="gmail_extra">
<br>
<br>
<div class="gmail_quote">On Fri, May 2, 2014 at 2:10 PM, jjs -
mainphrame <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:jjs@mainphrame.com" target="_blank">jjs@mainphrame.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">You know the saying, "when something seems
too good to be true"...
<div><br>
</div>
<div>I just installed centos 6.5 and openvz on an older
machine, and when I built an ubuntu 12.04 CT I noticed
that ploop is now the default layout. Cool. So I built
another ubuntu12.04 CT, identical in every way except
that I specified smifs, so I could do a quick
performance comparison.</div>
<div><br>
</div>
<div>First I did a quick timed dd run, then I ran dbench
with varying numbers of clients.</div>
<div><br>
</div>
<div>The simfs CT showed performance roughly similar to
the host, which was not too surprising.</div>
<div>What did surprise me was that the ploop CT showed
performance which was significantly better than the
host, in both the dd test and the dbench tests.</div>
<div><br>
</div>
<div>I know someone will tell me "dbench is a terrible
benchmark" but it's also a standard. Of course, if
anyone knows a "better" benchmark, I'd love to try it.</div>
<div><br>
</div>
<div>Regards,</div>
<div><br>
</div>
<div>J J</div>
</div>
</blockquote>
</div>
<br>
</div>
<br>
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