<div dir="ltr"><div>I took a simple 32-atom supercell of aluminum. Here is the input:</div><div><pre class="gmail-default gmail-s-code-block"><code class="gmail-hljs gmail-language-coffeescript">control
calculation=<span class="gmail-hljs-string">'scf'</span>
restart_mode=<span class="gmail-hljs-string">'from_scratch'</span>,
pseudo_dir = <span class="gmail-hljs-string">'.'</span>
outdir=.<span class="gmail-hljs-regexp">/tmp/</span>,
prefix=<span class="gmail-hljs-string">'al'</span>
tprnfor = .<span class="gmail-hljs-literal">true</span>.
tstress = .<span class="gmail-hljs-literal">true</span>.
disk_io=<span class="gmail-hljs-string">'none'</span>
/
&system
ibrav= <span class="gmail-hljs-number">0</span>, A=<span class="gmail-hljs-number">4.05</span>, nat= <span class="gmail-hljs-number">32</span>, ntyp= <span class="gmail-hljs-number">1</span>, ecutwfc =<span class="gmail-hljs-number">60.0</span>,
occupations=<span class="gmail-hljs-string">'smearing'</span>, smearing=<span class="gmail-hljs-string">'marzari-vanderbilt'</span>, degauss=<span class="gmail-hljs-number">0.05</span>
/
&electrons
diagonalization=<span class="gmail-hljs-string">'david'</span>
mixing_beta = <span class="gmail-hljs-number">0.7</span>
/
CELL_PARAMETERS alat
<span class="gmail-hljs-number">2</span> <span class="gmail-hljs-number">0</span> <span class="gmail-hljs-number">0</span>
<span class="gmail-hljs-number">0</span> <span class="gmail-hljs-number">2</span> <span class="gmail-hljs-number">0</span>
<span class="gmail-hljs-number">0</span> <span class="gmail-hljs-number">0</span> <span class="gmail-hljs-number">2</span>
ATOMIC_SPECIES
Al <span class="gmail-hljs-number">26.98</span> Al.pbe-n-kjpaw_psl<span class="gmail-hljs-number">.1</span><span class="gmail-hljs-number">.0</span><span class="gmail-hljs-number">.0</span>.UPF
ATOMIC_POSITIONS crystal
Al <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.00000000</span>
Al <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.00000000</span>
Al <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.25000000</span>
Al <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.25000000</span>
Al <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.00000000</span>
Al <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.00000000</span>
Al <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.25000000</span>
Al <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.25000000</span>
Al <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.00000000</span>
Al <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.00000000</span>
Al <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.25000000</span>
Al <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.25000000</span>
Al <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.00000000</span>
Al <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.00000000</span>
Al <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.25000000</span>
Al <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.25000000</span>
Al <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.50000000</span>
Al <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.50000000</span>
Al <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.75000000</span>
Al <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.75000000</span>
Al <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.50000000</span>
Al <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.50000000</span>
Al <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.75000000</span>
Al <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.75000000</span>
Al <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.50000000</span>
Al <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.50000000</span>
Al <span class="gmail-hljs-number">0.25000000</span> <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.75000000</span>
Al <span class="gmail-hljs-number">0.00000000</span> <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.75000000</span>
Al <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.50000000</span>
Al <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.50000000</span>
Al <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.75000000</span>
Al <span class="gmail-hljs-number">0.50000000</span> <span class="gmail-hljs-number">0.75000000</span> <span class="gmail-hljs-number">0.75000000</span>
K_POINTS automatic
<span class="gmail-hljs-number">11</span> <span class="gmail-hljs-number">11</span> <span class="gmail-hljs-number">11</span> <span class="gmail-hljs-number">0</span> <span class="gmail-hljs-number">0</span> <span class="gmail-hljs-number">0<br><br><br><br><br></span></code></pre><p>Here, I am running on single node with 48 processor with different number of <code>nk</code>and <code>nb</code></p>
<p>For example :<br>
<code>mpiexec.hydra -np 48 /USERS/pranav/compilation/q-e-qe-6.8/bin/pw.x -in <a href="http://al.scf.david.in">al.scf.david.in</a> -nk 3 -nb 4</code></p>
<p>In First study, I varied <code>nk</code> while fixed <code>nb</code>=1. Here is the result</p><pre class="gmail-default gmail-s-code-block"><code class="gmail-hljs gmail-language-css"><b>nk nb <span class="gmail-hljs-selector-tag">time</span>(sec)</b>
<span class="gmail-hljs-number">1</span> <span class="gmail-hljs-number">1</span> <span class="gmail-hljs-number">206</span>
<span class="gmail-hljs-number">2</span> <span class="gmail-hljs-number">1</span> <span class="gmail-hljs-number">163</span>
<span class="gmail-hljs-number">3</span> <span class="gmail-hljs-number">1</span> <span class="gmail-hljs-number">144</span>
<span class="gmail-hljs-number">4</span> <span class="gmail-hljs-number">1</span> <span class="gmail-hljs-number">138</span>
<span class="gmail-hljs-number">6</span> <span class="gmail-hljs-number">1</span> <span class="gmail-hljs-number">138</span>
<span class="gmail-hljs-number">8</span> <span class="gmail-hljs-number">1</span> <span class="gmail-hljs-number">131</span>
<span class="gmail-hljs-number">12</span> <span class="gmail-hljs-number">1</span> <span class="gmail-hljs-number">141</span></code></pre>
<p>In second run, I fixed <code>nk</code> at 3 and varied <code>nb</code> and
Here is the result</p><pre class="gmail-default gmail-s-code-block"><code class="gmail-hljs gmail-language-css"><b>nk nb <span class="gmail-hljs-selector-tag">time</span>(sec)</b>
<span class="gmail-hljs-number">3</span> <span class="gmail-hljs-number">1</span> <span class="gmail-hljs-number">144</span>
<span class="gmail-hljs-number">3</span> <span class="gmail-hljs-number">2</span> <span class="gmail-hljs-number">181</span>
<span class="gmail-hljs-number">3</span> <span class="gmail-hljs-number">4</span> <span class="gmail-hljs-number">255</span>
<span class="gmail-hljs-number">3</span> <span class="gmail-hljs-number">8</span> <span class="gmail-hljs-number">426</span></code></pre>
<p>Why is run-time increasing with increase in <code>nb</code> in second run? I was hoping for decreasing in trend.</p>
<p><br>
<strong>Note: QE v6. 8 is compiled with intel-oneapi and internal FFT library</strong></p></div><br>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><img src="https://docs.google.com/uc?export=download&id=1_INvSQIZtuw14diRdyuYvVEW7oN_w5Q1&revid=0B8Mrh5Yn7c7Na1pqWndGNzJPT0xEa2pVbkcxK1krVDBMZUhnPQ" width="200" height="75"><br></div><div dir="ltr">PRANAV KUMAR</div><div dir="ltr"> Research Scholar<br><div>IIT MADRAS (AM18D011)</div><div><br></div><div><br></div></div></div></div></div></div></div></div>