<br><br><div class="gmail_quote">On Wed, Dec 3, 2008 at 4:51 PM, Tony Travis <span dir="ltr"><<a href="mailto:ajt@rri.sari.ac.uk">ajt@rri.sari.ac.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Chris Rowson wrote:<br> > [...]<br> <div class="Ih2E3d">> I've always used 32bit edition on servers myself. I've heard horror<br> > stories about perl scripts using twice as much memory under 64bit etc,<br> > etc.... I've never tested PAE with more than 4GB of RAM - I had heard<br> > about the single process limitation, but as I only had 4GB to play with,<br> > I've never had the opportunity to hit that limit!<br> <br> </div>Hello, Chris.<br> <br> In fact you can only alloc() 2GB in a contiguous block if you have 4GB<br> RAM installed. You can get somewhere near 3GB in total per process if<br> you don't care about memory fragmentation with 4GB RAM installed.<br> <br> Things improve quite a lot with 8GB installed, but you still can't get<br>  >4GB per process using PAE. For many programs that's not a problem, and<br> you're right about 64-bit doubling the size of memory usage in certain<br> situations. Actually, I don't think 64-bit is worth it unless you have<br> very BIG memory problems to solve. PAE is quite good if you want to run<br> multiple instances of programs that have < 4GB memory footprints.<br> <div><div></div><div class="Wj3C7c"><br> Bye,<br> <br>        Tony.<br> --<br> Dr. A.J.Travis, University of Aberdeen, Rowett Institute of Nutrition<br> and Health, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, Scotland, UK<br> tel +44(0)1224 712751, fax +44(0)1224 716687, <a href="http://www.rowett.ac.uk" target="_blank">http://www.rowett.ac.uk</a><br> mailto:<a href="mailto:a.travis@abdn.ac.uk">a.travis@abdn.ac.uk</a>, <a href="http://bioinformatics.rri.sari.ac.uk/%7Eajt" target="_blank">http://bioinformatics.rri.sari.ac.uk/~ajt</a><br> </div></div></blockquote><div><br>Thanks Tony,<br><br>As ever you helped expand my mind on the list :-)<br><br>Chris<br></div></div><br>