Where can I read about extents and xfs? <div><br><div class="gmail_quote">On Sun, Jan 13, 2013 at 4:26 AM, Florian Weimer <span dir="ltr"><<a href="mailto:fw@deneb.enyo.de" target="_blank">fw@deneb.enyo.de</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">* Bradley C. Kuszmaul:<br>
<div class="im"><br>
> The question I have: What will happen to the performance of other<br>
> threads doing read() and write() operations? Will hole-punching slow<br>
> down the other read() and write() operations running in other threads?<br>
<br>
</div>Assuming that hole-punching creates extents (not sure if it does, you<br>
can check with filefrag or other tools), you might experience a<br>
slowdown during open(), when the entire list of extents is read from<br>
disk.<br>
<br>
I once was a heavy Berkeley DB user and had files with dozens of<br>
gigabytes containing hundreds of thousands of extents, and open()<br>
times in the order of minutes were not unusual with a cold cache and<br>
other concurrent read activities from the same RAID device. But these<br>
files grew over time—perhaps hole punching results in better locality<br>
of the extent data, so that reading it doesn't take so much time in<br>
your case.<br>
</blockquote></div><br></div>