<div><br><div class="gmail_quote">On Sat, Aug 6, 2011 at 12:37 PM, Daniel Baluta <span dir="ltr"><<a href="mailto:daniel.baluta@gmail.com">daniel.baluta@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div class="im">On Sat, Aug 6, 2011 at 10:17 PM, subin gangadharan<br>
<<a href="mailto:subingangadharan@gmail.com">subingangadharan@gmail.com</a>> wrote:<br>
> Hi,<br>
> This is a text excerpt from the article [1].<br>
> Below paragraph I didn't understand quite well.Mainly in bold letters.Could<br>
> anybody please explain how this will lead to an infinite loop.<br>
<br>
</div>It seems self-explanatory. Most atomic ops are written to retry upon a failed<br>
store, and on PowerPC an atomic store to an unaligned address always fails,<br>
thus the processor will infinitely try to store the value, without having<br>
the chance to fix the unaligned access (as would have happened if an exception<br>
was thrown).<br>
<div class="im"><br>
><br>
> Unfortunately, the PowerPC does not throw an exception when atomically<br>
> storing to an unaligned address. Instead, the store simply always fails.<br>
> This is bad because most atomic functions are written to retry upon a failed<br>
> store, under the assumption they were preempted. These two circumstances<br>
> combine to where your program will go into an infinite loop if you attempt<br>
> to atomically store to an unaligned address. Oops.<br>
<br>
</div>thanks,<br>
<font color="#888888">Daniel.<br></font></blockquote>Thanks Daniel,<div>My bad, I was trying to connect the page fault explained before that paragraph and this one.</div><div>Hence I got confused,again thanks for clarifying it. </div>
</div><br><br clear="all"><br>-- <br>With Regards<br>Subin Gangadharan<br><br><div>Everything should be made as simple as possible,but not simpler.</div><br>
</div>