Wikipedia:Reference desk/Archives/Computing/2015 February 7

= February 7 =

Looking for a blog post
Hi, I'm looking for a fairly recent blog post. The author was looking at how to reduce (sum, or maybe count occurrences) an array quickly. I think this was specifically on a single core of a modern Intel CPU - i.e. looking at microarchitectural influences, rather than throwing relatively coarse parallelism at the problem. I do remember a specific trick used was to keep multiple copies of the reduction variable, because even on a single thread it allowed the scheduler to make better use of ILP in an unrolled loop (or similar). Does anyone have a link to the post I'm thinking of? Thanks. 82.13.241.56 (talk) 03:26, 7 February 2015 (UTC)

Qatar IP addresses
Does Qatar have "normal" IP addresses yet? MediaWiki:Blockiptext still mentions only Special:Contributions/82.148.96.68 and Special:Contributions/82.148.96.69, but both of them have been inactive for several years now. Nyttend (talk) 14:29, 7 February 2015 (UTC)

Could a virus written in Java run everywhere?
That's what Sun Microsystems says "write once, run everywhere."--Noopolo (talk) 20:14, 7 February 2015 (UTC)


 * It wouldn't run if the Java runtime had never been installed on the computer. I'm not enough of an expert to know if there might be a version of the Java runtime hidden away someplace where it wouldn't be obvious by browsing the add/remove program list provided by the operating system. Jc3s5h (talk) 20:18, 7 February 2015 (UTC)


 * I believe it could. It would be reminiscent of a Microsoft Word macro virus that infected Windows and Mac versions of Word alike. —Steve Summit (talk) 23:14, 7 February 2015 (UTC)


 * "Everywhere" is a slight exaggeration, but a Java bytecode can run in a surprising number of places.
 * However, while the possibility of Java viruses was proven way back in the 90s. (See Strange Brew (computer virus)), They're rare, and I'm not aware of one that can jump platforms.
 * Most situations where Java is used are sandboxed pretty heavily. Also, the logic needed to find and then infect an Android program would be very different than the logic needed to find and infect a desktop java app. An app that could jump platforms like that would need to be very sophisticated. APL (talk) 23:19, 8 February 2015 (UTC)
 * (Fixed your link syntax) Good point on platform jumping. Also Windows still has by far the highest install numbers for desktops according to Usage_share_of_operating_systems, so why would a malicious virus-maker bother going through the extra effort? SemanticMantis (talk) 14:33, 9 February 2015 (UTC)