Hyperthreading - hype or benefit for aveage user ?

Capt'n Midnight

If your OS / Apps don't support hyperthreading then there is no benefit.

I still haven't found a list of real world apps with hyperthreading benefits, just the usual hype and theory, nothing that says that Word spell checks 20% faster or anything like that. So apart from gaming and video processing does it have any benefit on the corporate or home user desktop ?

Does anyone have any links to performance improvements in real world apps ?


http://news.zdnet.co.uk/0,39020330,39237341,00.htm - claims SQL slowed down by hyperthreading

The on-chip cache exists to speed operation by keeping copies of recently accessed data where it can be accessed without recourse to main system memory — which is much slower by comparison. Where multiple threads access different parts of memory but are simultaneously processed by the chip's Hyperthreading Technology, the shared cache cannot keep up with their alternate demands and performance falls dramatically, according to analysis by Ocks and Ibbotson.

This has been known for a long time. Hyper Threading helps significantly when you are using nonoptimised or programs that require the ability to execute function steps before continuing. It even helps running many small programs. But when you have a optimised program that retains system saturation the Hyper Threading just provider more things to a CPU that can not do any more.

reminds me of the hype of the pentium running 30% (or whatever) faster than a 486, yes, but only with optimised code and the 486 also benefited about 15% from optimised code so the real gain, apart from larger cache, was less until the new instuctions were in use.

http://blogs.msdn.com/slavao/archive/2005/11/12/492119.aspx - original microsoft blog about SQL hit in some circumstances.

duridian

I can't say I find it makes any real difference in any of the programs I use on my 3.2 Prescott, especially if I am only using one application. Where it does show it's merit for me is for example if I am encoding a video on the Pentium, I can let that task running and still use other programs without as much of a performance hit. With the video encoding, it is still easy to switch between other running tasks like web browser, word processor or similar. I haven't actually tried running a game at the same time, but I suppose it might be possible once the game isn't F.E.A.R. or something like that.
Doing the video encode job on either of my other systems, a Venice 3500 and a Barton 3200, results in the machine slowing dramatically at any other running tasks, even switching between app windows slows down a lot. I know that Intel have traditionally been better at encoding stuff, but this is not really a test of how well the pc encodes, as much as it is a test of how well everything else will run while the machine encodes. Anyway I have found much the same thing happens when compressing large amounts of data (2-3GB)using 7zip's max compression, so it isn't just on video encoding it happens. Since the machines are all pretty powerful, I have always put this "better at multiple apps ability" down to the hyperthreading of the P4, but in the one application only running situation I have not found any app where HT makes a difference really TBH. I guess not that many programs have been optimised to make use of it.

Capt'n Midnight

Forgot about 7zip http://www.boards.ie/vbulletin/showpost.php?p=3527895&postcount=14

me wrote:

So far the only end user app I've seen speed up is 7za.exe the command line version of 7zip !

Still most of our users won't be encoding video in the background.

astrofool

it really only makes a difference to multitaskers, but is not anywhere near as good as dual core.

It is turned off by default on server machines (or should be).

DemonOfTheFall

I say yes, it is well worth it for a lot of average users. If you have a virus scanner, firewall, anti-spyware and whatever other crap running in the background it does add a good level of performance to doing anything.

One absolutely glaring example of where it's very useful : On my A64 I can't listen to music while gaming. Well, I kind of can if I change process priorities, but it'll have a bit of an impact on frames nomatter how I do it. On any P4 I've seen this isn't an issue at all.

jesus_thats_gre

Definetly.. After using a HT enabled P4 (2.8GHz with 512mb of RAM) for a year and then moving to a Pentium M based laptop (2.26 GHz with 2gigs of RAM), I definetly notice a big difference.