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<div class="gmail_quote">On Thu, Jan 20, 2011 at 12:11 PM, Dave Chinner <span dir="ltr"><<a href="mailto:david@fromorbit.com">david@fromorbit.com</a>></span> wrote:<br>
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<div class="im">On Thu, Jan 20, 2011 at 11:37:44AM +0530, Amit Sahrawat wrote:<br>> Hi,<br>><br></div>
<div class="im">> I will try to find out the cause for this.<br>> Meanwhile, just a small request/suggestion - in the past this type of<br>> testcases have helped us in finding many problems in XFS.<br>> Can something like this be added to xfstests? This might help.<br>
<br></div>Definitely. We're always looking for more people to add tests that<br>expose problems to xfstests. :) We try to keep individual test<br>runtime to as little as possible - under 5 minutes for the auto<br>group, under 15s for the quick group, but by the looks of it the<br>
test you are running doesn't take that long to run.<br></blockquote>
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<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">>> Yes, the test case we are using is not taking much time this time to cause issue - around 3-4 minutes.<br>
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<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">FWIW, there are already tests that cause worst case filesystem<br>fragmentation as part of their test setup (e.g. test 042) but the<br>
coverage of such issues could definitely be improved. Also, the way<br>we generate fragmented filesystems - by writing files and then<br>removing a subset - could be greatly sped up by preallocation and<br>hole punching. There's no need to write data when we could just use<br>
unwritten extents to do the same thing...<br>
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<div class="h5">>> We basically fragment by doing following steps:</div></div></blockquote>
<div> Full the disk with same size files (in this case it is 16k)</div>
<div>Then, randomly remove files from the disk.</div>
<div>Doing so, allows us to create files as per our requirement - complete control when we need - single extent, multiple extent files, Btree format file, single leaf file, multiple leaf file - It allows us ease to use XFS.</div>
<div>I hope you are getting what I am trying to say. </div>
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<div>But, in this case - it starts causing issue at the very first stage - just copying 16k file to make disk full. </div>
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<div>Thanks,</div>
<div>Amit Sahrawat</div>
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