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<br><div><div>On 14-Mar-08, at 5:14 PM, Valentin Micic wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"> <div><font face="Arial" size="2">Not when your application starts to swap-in and out because it is running out of RAM, </font></div></blockquote><div><br class="webkit-block-placeholder"></div><div>That should never happen! Are you sure you've got the right analysis?</div><div><br class="webkit-block-placeholder"></div><div>--Toby</div><br><blockquote type="cite"><div><font face="Arial" size="2">and yet you still have plenty of RAM occupied by files that have been open and read, say few months ago, and no longer needed. Now, consider 64GB RAM of which 32 GB is occupied by cache. </font></div> <div><font face="Arial" size="2"></font> </div> <div><font face="Arial" size="2">Between faster and fast enough, I'm always inclined to select fast enough, especially if that's going to allow me to use memory the way I need to vs. the way OS forces me to.</font></div> <div><font face="Arial" size="2"></font> </div> <div><font face="Arial" size="2">V.</font></div> <div><font face="Arial" size="2"></font> </div> <blockquote style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <div style="FONT: 10pt arial">----- Original Message ----- </div> <div style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><b>From:</b> <a title="rapsey@gmail.com" href="mailto:rapsey@gmail.com">Rapsey</a> </div> <div style="FONT: 10pt arial"><b>To:</b> <a title="erlang-questions@erlang.org" href="mailto:erlang-questions@erlang.org">erlang-questions@erlang.org</a> </div> <div style="FONT: 10pt arial"><b>Sent:</b> Friday, March 14, 2008 10:32 PM</div> <div style="FONT: 10pt arial"><b>Subject:</b> Re: [erlang-questions] Linux O_DIRECT flag</div> <div><br></div>I don't understand. Why is that a problem? Access to RAM will always be much faster than access to a storage array. <br><br><br> <div class="gmail_quote">On Fri, Mar 14, 2008 at 8:45 PM, Valentin Micic <<a href="mailto:valentin@pixie.co.za">valentin@pixie.co.za</a>> wrote:<br> <blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">Dear all,<br><br>One thing that has to make a top 10 most-likely-to-frustrate-you features in<br>LINUX is its uncontrollable usage of memory for I/O caching. Whilst good for<br>most applications, it seems quite redundant if you connect a big storage<br>array that has a cache on its own.<br>After a brief investigation regarding ones ability to bypass the cache<br>(performed by our hardware supplier), I've been told that an application may<br>bypass the cache by porviding additional flag to "open" system call --<br>O_DIRECT to be more specific. I assume that <a href="file:open/2">file:open/2</a> does not support<br>this flag, so I'd like to ask, before we start hacking around: is there an<br>easy way to expose this flag, and would you consider it for inclusion in one<br>of the next releases. Provided that O_DIRECT does what we think it does, of<br>course.<br><br>Thanks in advance,<br><br>Valenitn.<br><br>_______________________________________________<br>erlang-questions mailing list<br><a href="mailto:erlang-questions@erlang.org">erlang-questions@erlang.org</a><br><a href="http://www.erlang.org/mailman/listinfo/erlang-questions" target="_blank">http://www.erlang.org/mailman/listinfo/erlang-questions</a><br></blockquote></div><br><div> <br class="khtml-block-placeholder"></div><hr><div><br class="khtml-block-placeholder"></div>_______________________________________________<br>erlang-questions mailing list<br><a href="mailto:erlang-questions@erlang.org">erlang-questions@erlang.org</a><br>http://www.erlang.org/mailman/listinfo/erlang-questions</blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">erlang-questions mailing list</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="mailto:erlang-questions@erlang.org">erlang-questions@erlang.org</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="http://www.erlang.org/mailman/listinfo/erlang-questions">http://www.erlang.org/mailman/listinfo/erlang-questions</a></div> </blockquote></div><br></body></html>