<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Dear Shaofeng,<br>
<br>
scaling depends in general by number of factors. Moreover, you are
providing no information about your input system. <br>
This results in a too generic question which is hard to answer if
not making other questions (to be generally avoided on mailing
lists).<br>
<br>
I reckon you registered a better scaling from 2 to 4 cores and from
4 to 8 cores as you are reporting the issue only about scaling from
8 to 16 cores. <br>
By experience I would say that you are dumping into two possible
scenarios:<br>
<br>
1) You reached a scaling limits. <br>
In general px.x scales well up to 16 processes except you are
working with a really small system.<br>
<br>
2) You are actually working on a two quad-core CPU system with
hyper-threading enabled. <br>
The hyper-threading extends to 8 the number of virtual cores per CPU
socket (your /proc/cpuinfo reports 16 cores). <br>
In most cases, high-performance software applications (such as QE)
do not benefit of this feature scaling only up to the number of
physical cores available. <br>
Possibly you can google the model of you processor (see
/proc/cpuinfo) to verify the number of physical cores on each CPU
socket.<br>
<br>
Regards,<br>
<br>
Ivan<br>
<br>
<br>
<div class="moz-cite-prefix">On 15/09/2015 03:40, Shaofeng Wang
wrote:<br>
</div>
<blockquote cite="mid:DE8414F775774904B1FAFBD242E9D5D2@Wanglaptop"
type="cite">
<div dir="ltr">
<div style="FONT-FAMILY: 'Century'; COLOR: #000000; FONT-SIZE:
14pt">
<div><font size="4">Dear all,</font></div>
<div> </div>
<div><font size="4">I got a server computer equipped with two
8 core cpus. I installed intel fortran compiler (12.1) and
openmpi (1.6.5). No errors took place during installation.
Then I compiled parallel quantum esspresso (5.2.0) and the
program run correctly. However, I found pw.x runs at very
similar speed with 8 cores or 16 cores. Could any expert
show me how to improve the calculation speed?</font></div>
<div> </div>
<div><font size="4">The make.sys file is attached.</font></div>
<div> </div>
<div><font size="4">Thanks in advance.</font></div>
<div> </div>
<div><font size="4">Shaofeng</font></div>
<div style="FONT-FAMILY: 'Century'; COLOR: #000000; FONT-SIZE:
14pt">--------------------------------------<br>
Shaofeng Wang, Ph.D of Geochemistry<br>
Environmental Molecular Science Group<br>
Institute of Applied Ecology, Chinese Academy of Sciences<br>
Shenyang, 110016, China<br>
<a class="moz-txt-link-abbreviated" href="mailto:wangshaofeng@iae.ac.cn">wangshaofeng@iae.ac.cn</a><br>
<a class="moz-txt-link-abbreviated" href="http://www.iae.cas.cn">www.iae.cas.cn</a><br>
<br>
</div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Pw_forum mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a>
<a class="moz-txt-link-freetext" href="http://pwscf.org/mailman/listinfo/pw_forum">http://pwscf.org/mailman/listinfo/pw_forum</a></pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">
</pre>
</body>
</html>