On Thu, Aug 30, 2012 at 01:28:05PM +0800, Bret Busby wrote: > On Wed, 29 Aug 2012, Bob Proulx wrote: > [cut] > > I enable javascript in Opera, as I use it for most online financial > transactions, including online banking, and, of the (more?) major > web browsers, as far as I am aware, opera is the only one that has > not yet been breached as far as security is concerned. I have seen > multiple CERT advisories for the Mozilla and Microsoft web browsers. Be aware that fewer advisories may or may not be a good thing here. Opera is proprietary (closed source) so the only way to test it for security problems is to attack the compiled browser. Admittedly, this is the same with Internet Explorer, though but that has a higher market share. [cut[ > > I had understood that the operating system (in the case or Linux, > the kernel?) controls memory management, so that, depending on the > settings, once a threshold, for example, 50% of RAM, is used, the > operating system would start paging memory, using the allocated swap > space, to provide system stability until both swap space and RAM are > totally used, then crash, rather than just using up all of the RAM > and mostly ignoring the swap space and crashing the system, without > significantly using the swap space. No. The Linux philosophy is that you paid good money to have all that nice, fast RAM in your system so why not make use of it. There will usually be a certain amount of RAM free, but the kernel prefers to keep things like buffers, disk caches etc filling your RAM rather than needlessly discarding them (If you discard cached data and need it again, you have to take the hit of reading from disk. But if you need the RAM for something else such as an application, then THAT's the time to discard some cached data). However, as you've noted, once you run out of RAM, the kernel should start moving the less-frequently used pages into Swap. In theory, the OOM-killer should only come into play when both are full. However, I can see a couple of situations where that may not happen: * A single application (Opera, in this case) is requesting more memory than you have RAM. In this case, the rest of the system is swapped out (hence the hideous responsiveness) but not using all of your swap, and eventually the kernel says "I'm sorry Dave...." * You are on a 32-bit system and an application has requested more memory than the kernel can address (3-4GB depending on kernel options). > > I am apparently wrong. > > It used to work, much better, with Debian 3 and 3.1; I can't > remember much about Debian 4, then, as previously mentioned, I had > the problem and the solution as such, with Debian 5, and, now, with > Debian 6, memory management appears to simply not work, making > Debian 6, at least in the 64 bit version, of the nature of the > attributes used to describe the experimental version of Debian. As this appears to be a problem with Opera, have you considered raising the issue with Opera's Support (http://www.opera.com/support/)?
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