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Hi Richard,<br>
<br>
Sequential describes I/O accesses that are just at any offset
greater than the immediately preceding I/O operation. For instance,
say I write 100 bytes at offset 0, then my next access is a read at
offset 500 -- that would be a sequential access.<br>
<br>
Consecutive is more strict in that it requires that the current
operation be at the offset immediately following the end of the
preceding access's end. An example would be if I write 100 bytes at
offset 0, then read at offset 100, instead. So, all consecutive
accesses are also sequential but not vice versa.<br>
<br>
Note that there is no distinction between the types of the 2
operations. If the current operation is a write, we don't care if
the previous operation was a read or a write, just the ending offset
of it. <br>
<br>
I should probably mention that we have fixed this graph to be more
clear in the new development branch of darshan we are preparing to
release, as it has been a source of confusion for a number of
people.<br>
<br>
--Shane<br>
<br>
<div class="moz-cite-prefix">On 09/09/2015 03:23 PM, Hedges, Richard
M. wrote:<br>
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<div>In the default report, the fourth plot (labelled ?I/O
Pattern”) distinguishes between ”Consecutive” and
“Sequential” . Could someone explain the distinction for
me?</div>
<div><br>
</div>
<div>Thanks,</div>
<div>- Richard</div>
<div>
<div><br>
</div>
<div>====================================================</div>
<div><br>
</div>
<div>Richard Hedges</div>
<div>Customer Support and Test - File Systems Project</div>
<div>Development Environment Group - Livermore Computing</div>
<div>Lawrence Livermore National Laboratory</div>
<div>7000 East Avenue, MS L-557</div>
<div>Livermore, CA 94551</div>
<div><br>
</div>
<div>v: (925) 423-2699</div>
<div>f: (925) 423-6961</div>
<div>E: <a class="moz-txt-link-abbreviated" href="mailto:richard-hedges@llnl.gov">richard-hedges@llnl.gov</a></div>
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