daniel de graaf - Slashdot User

Comment Re:What Has Changed? (Score 1) 900

by daniel de graaf on Wednesday October 01, 2008 @10:06PM (#25228117) Attached to: How Big Should My Swap Be?

You can turn off overcommit in Linux if want to - most people find the default behavior more useful since many applications allocate memory they do not need to use, and don't handle out of memory errors gracefully. Change the sysctl "vm.overcommit_memory" to 2, and see "Documentation/vm/overcommit-accounting" in the linux kernel source for related sysctls.

There are occasions where you might want to use a lot of swap, if there are one-time-run applications that use a ton of RAM to do something like image manipulation/scientific computing/whatever. Those might be rare, but it would be very irritating to get out-of-memory errors just because the kernel doesn't feel like using swap.

When the OOM killer is invoked, the application isn't usually allocating memory - it's using memory that it has allocated before and that the kernel overcommitted on. So there's no good way to send an out-of-memory error other than by something like a signal handler. I think the reason this isn't done is because the signal handler would likely need to allocate RAM to run (maybe to get its code paged off disk) and this wouldn't help with the memory pressure.

China Vows to Stop the Rain 214

Posted by samzenpus on Thursday January 31, 2008 @03:01PM from the way-ahead-of-the-germ-warfare-division dept.

Since the Olympic stadium doesn't have a roof, the Beijing Meteorological Bureau has been given the task of making sure the games remain dry. According to Zhang Qian, head of weather manipulation (best title to have on a business card ever) at the bureau, they've had success with light rain but heavy rain remains tough to control. I see a hurricane cannon in some lucky country's future.

Schneier's Keynote At Linux.conf.au 138

Posted by kdawson on Tuesday January 29, 2008 @10:49PM from the necessary-security-theater dept.

Stony Stevenson writes "Computer security expert Bruce Schneier took a swipe at a number of sacred cows of security including RFID tags, national ID cards, and public CCTV security cameras in his keynote address to Linux.conf.au (currently being held in Melbourne, Australia). These technologies were all examples of security products tailored to provide the perception of security rather than tackling actual security risks, Schneier said. The discussion of public security — which has always been clouded by emotional decision making — has been railroaded by groups with vested interests such as security vendors and political groups, he claimed. 'For most of my career I would insult "security theater" and "snake oil" for being dumb. In fact, they're not dumb. As security designers we need to address both the feeling and the reality of security. We can't ignore one. It's not enough to make someone secure, that person needs to also realize they've been made secure. If no-one realizes it, no-one's going to buy it,' Schneier said."

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