<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<p><br>
</p>
<div class="moz-cite-prefix">On 04.09.24 15:59, Henrik Cednert
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:GVYP280MB0574EBA8A7A2989184101484EC9C2@GVYP280MB0574.SWEP280.PROD.OUTLOOK.COM">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<style type="text/css" style="display:none;">P {margin-top:0;margin-bottom:0;}</style>
<div class="elementToProof"
style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Thanks Uwe</div>
</blockquote>
<br>
<p><br>
</p>
<p><span style="white-space: pre-wrap">Just saw: the app seems to have issued IO requests not sequentially but in bunches.</span></p>
<p><span style="white-space: pre-wrap">what is apparent (but I have not recognized it before): </span></p>
<p><span style="white-space: pre-wrap">
</span></p>
<p><span style="white-space: pre-wrap">after such a bunch of IOs, the next bunch is typically issued when the longest-taking IO from the prious bunch was completed. For example: </span></p>
<p><span style="white-space: pre-wrap">
</span></p>
<p><span style="white-space: pre-wrap">
</span></p>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.341629 R data 17:805453824 16384 3,993
cli C0A82DD5:63877BDA 192.168.45.213</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.341629 R data 6:1720532992 16384 27,471
cli C0A82DD5:63877BCE 192.168.45.214</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.341629 R data 14:1720532992 16384 44,953
cli C0A82DD5:63877BD6 192.168.45.214</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">3
read IOs issued at 13:24:59.341629, longest taking 44.953ms.
59.341629+0.044953=59.386582, which is 1ms before the next IO req
is issued at 13:24:59.387584</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">13:24:59.387584
R data 17:805453824 16384 5,990 cli
C0A82DD5:63877BDA 192.168.45.213</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">that
one takes just 5.990ms , the next bunch of IO reqs is seen 6.988
ms later (i.e. again the service time plus about 1 ms): <br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.394572 R data 17:805453824 16384 7,993
cli C0A82DD5:63877BDA 192.168.45.213</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">now
a triplet of IOs again, but one of them taking very long: <br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.402565 R data 25:805453824 16384 4,991
cli C0A82DD5:63877BE2 192.168.45.213</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.402565 R data 22:1720532992 16384 26,309
cli C0A82DD5:63877BDF 192.168.45.214</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.402565 R data 7:1720532992 16384 142,856
cli C0A82DD5:63877BCF 192.168.45.213</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">That
incurs the expected delay of 143.854ms : <br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">13:24:59.546419
R data 25:805453824 16384 7,992 cli
C0A82DD5:63877BE2 192.168.45.213</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">etc.
pp. <br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><br>
</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.556408 R data 25:805453824 16384 7,987
cli C0A82DD5:63877BE2 192.168.45.213</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.564395 R data 10:805453824 16384 5,505
cli C0A82DD5:63877BD2 192.168.45.214</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.564395 R data 23:1720532992 16384 28,053
cli C0A82DD5:63877BE0 192.168.45.213</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.564395 R data 15:1720532992 16384 33,044
cli C0A82DD5:63877BD8 192.168.45.213</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.598437 R data 10:805453824 16384 5,504
cli C0A82DD5:63877BD2 192.168.45.214</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.604939 R data 18:805453824 16384 4,993
cli C0A82DD5:63877BDB 192.168.45.214</div>
<div
style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
13:24:59.604939 R data 8:1720532992 16384 36,015
cli C0A82DD5:63877BD0 192.168.45.214</div>
<p></p>
<p><span style="white-space: pre-wrap">...</span></p>
<p><span style="white-space: pre-wrap">
</span></p>
<p><span style="white-space: pre-wrap">so there is some parallelization in IO, but using multiple threads should improve things as the app apparently still waits for IOs being performed. and of course with an otherwise unloaded storage and just one client, service times >25ms should not be seen and most should be 10...20ms. </span></p>
<p><span style="white-space: pre-wrap">
</span></p>
<p><span style="white-space: pre-wrap">Uwe </span></p>
<p><span style="white-space: pre-wrap">
</span></p>
<pre class="moz-signature" cols="72">--
Karlsruhe Institute of Technology (KIT)
Scientific Computing Centre (SCC)
Scientific Data Management (SDM)
Uwe Falke
Hermann-von-Helmholtz-Platz 1, Building 442, Room 187
D-76344 Eggenstein-Leopoldshafen
Tel: +49 721 608 28024
Email: <a class="moz-txt-link-abbreviated" href="mailto:uwe.falke@kit.edu">uwe.falke@kit.edu</a>
<a class="moz-txt-link-abbreviated" href="http://www.scc.kit.edu">www.scc.kit.edu</a>
Registered office:
Kaiserstraße 12, 76131 Karlsruhe, Germany
KIT – The Research University in the Helmholtz Association
</pre>
</body>
</html>