<div dir="ltr"><div dir="ltr">On Fri, Dec 17, 2021 at 6:42 AM pranav kumar <<a href="mailto:prnvkmr4@gmail.com">prnvkmr4@gmail.com</a>> wrote:</div><div dir="ltr"><br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><code><b>nk nb <span>time</span>(sec)</b> 
</code><div><pre><code><span>1</span> <span>1</span> <span>206</span>
<span>2</span> <span>1</span> <span>163</span>
<span>3</span> <span>1</span> <span>144</span>
<span>4</span> <span>1</span> <span>138</span>
<span>6</span> <span>1</span> <span>138</span>
<span>8</span> <span>1</span> <span>131</span>
<span>12</span> <span>1</span> <span>141</span></code></pre></div></div></blockquote><div>this is the expected behavior: you are decreasing the number of processors for plane-wave parallelization while increasing the number of processors for k-point parallelization. Given the size of the system (not too big) and the number of k-points (quite a lot) it is convenient to exploit also k-point parallelization.<br></div><div><br></div><div> The "band" parallelization should not be used as a replacement of plane-wave or k-point parallelization but only in addition to, for some specific cases (e.g. hybrid functionals)<br></div><div><br></div><div>Paolo<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>

<p>In second run, I fixed <code>nk</code> at 3 and varied <code>nb</code> and
Here is the result</p><pre><code><b>nk nb <span>time</span>(sec)</b> 
<span>3</span>  <span>1</span> <span>144</span>
<span>3</span>  <span>2</span> <span>181</span>
<span>3</span>  <span>4</span> <span>255</span>
<span>3</span>  <span>8</span> <span>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>
<b>Note: QE v6. 8 is compiled with intel-oneapi and internal FFT library</b></p></div><br>-- <br><div dir="ltr"><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>
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