Hyper-Threading considered harmfull

[LennonCook]

Originally posted by Hivetyrant: That's what I meant, as you said they can technicaly only process one thing at a time, but they switch between them so damn fast you don't notice.

Sure, but that's not hyperthreading, or even a processor function. That's an operating system function. The processor doesn't know about applications, it only does math. Cross-referencing with the Wikipedia article on it, Vaskez's explanation seems about right... especially the bit about "plain english" [img]smile.gif[/img]

EDIT: HTML hates whitespace... and here I was thinking they ignored each other.
EDIT (again): Took out a small bit of misinformation...

And here's Intel's explanation:

Hyper-Threading Technology enables this thread-level parallelism (TLP) by duplicating the architectural state on each processor, while sharing one set of processor execution resources. When scheduling threads, the operating system treats the two distinct architectural states as separate 'logical' processors. This allows multiprocessor capable software to run unmodified on twice as many logical processors.

[ 05-24-2005, 03:49 AM: Message edited by: LennonCook ]

[LennonCook]

Originally posted by RoSs_bg2_rox: Only thing is, hyperthreading isn't really used much these days anyway, as programs don't support it etc. And infact you might even see a performance loss in some games with it enabled.

Nonsense. Handling processor scheduling is an Operating System function - if some programs run slower with hyperthreading, it is the OS's fault.

[LennonCook]

Originally posted by Hivetyrant: AMD-64 Bit and Intel 64-Bit

64-bit processors don't have anything special in this regard - they can just handle wider values (= higher integers = more memory = later dates = alot of other stuff).

[LennonCook]

Originally posted by Charlie: What's RSA?

It's an algorithm for implenting assymetric key encryption. Basically, when someone can get your private key, they can read stuff that's been encrypted so that only you can read it, and they can sign private messages to make them look like they came from you.
In other words, this is not a good thing.

[Azeral]

dont mean to be a pain lennon but you just spammed four posts one after the other. (you would have told me off for it.) [img]tongue.gif[/img] (but all the info was very useful)

[ 05-24-2005, 06:01 AM: Message edited by: Azeral ]

[Charlie]

Vaskez, I've read your post a few times. It's brilliantly broken down. I see what you're saying and pretty much understand. Since reading the subsequent responses, new questions popped into my head. But I'll bow out, methinks, I've obviously bitten off more than I can chew.

Cheers for a well constructed answer.

Thanks for the tip on RSA as well Lennon.

One thing that kinda worries me is this ...I'm assuming that my home computer is a desktop computer.

single-user systems (i.e., desktop computers) are not affected.

followed up in the Q&A with..

Do I need to worry about my home computer? Probably not. This security flaw is primarily a problem for servers

"Probably" and "primarily" wouldn't instill much confidence if I was a home user running one of those processors.


P.S. I've tried to respond a couple of times but the forums, for me at least seem to go down with some regularity.

[ 05-24-2005, 09:00 PM: Message edited by: Charlie ]

[RoSs_bg2_rox]

Originally posted by LennonCook: quote: Originally posted by RoSs_bg2_rox: Only thing is, hyperthreading isn't really used much these days anyway, as programs don't support it etc. And infact you might even see a performance loss in some games with it enabled.

Nonsense. Handling processor scheduling is an Operating System function - if some programs run slower with hyperthreading, it is the OS's fault. [/QUOTE]I didn't say it wasn't the OS' fault though

[Vaskez]

*bows* thank you Charlie

I hope to read more about this someday. However, even though I literally don't play any games these days (don't think I've loaded a game for a few months now) I still don't have enough time to do everything I want (damn PhD takes up too much time ). Lying around are several issues of National Geographic, PC Magazine, IEEE Spectrum and IEEE Communications Magazine to be read, plus I've got loads of rap lyrics to translate

[ 05-25-2005, 09:14 PM: Message edited by: Vaskez ]

[andrewas]

Originally posted by Charlie: quote: single-user systems (i.e., desktop computers) are not affected.

followed up in the Q&A with..

Do I need to worry about my home computer? Probably not. This security flaw is primarily a problem for servers

"Probably" and "primarily" wouldn't instill much confidence if I was a home user running one of those processors.

[/QUOTE]That struck me as odd as well. As near as I can make out, desktop systems are as vulnerable as multi-user system. Its not all that hard to get software onto someones computer against their wishes, unless they use spyware scanners and so on. Many people still dont.

But how often does your PC have an interesting RSA key to steal? How often do you use your credit card on the net? And, would you even consider using your credit card on the net without making sure your system was spyware and virus free? So it shouldnt really be a problem. Besides, as well as stealing the RSA key, they'd need to intercept the data between your PC and the server to get the actual information. No, if I was going to try to steal peoples CC numbers, I'd use keylogging software.

Whereas a multi user system in a large corporation could be using RSA to distribute sensitive information which might be worth the effort.