Dual Xeon Hyperthreading

[tcngs]

Does any no if a dual Xeon 2.8ghz dedicated to just running steam based game would run any better turning off the hyperthreading or leaving it on?

[Defcon|Rich]

We have tested both ways and didn't notice any difference in performance.

[adamnp]

The only real difference I noticed was that you'll maintain a more steady ticrate ingame with HyperThreading Off...Does't affect the number of instances you can run or any of that garb. I remember way back having rich turn it on and off on a certain box, while we were testing stuff haha! Remember that? What a pain in the ass I was

 

The mind expands daily! Indulge

 

Howd you guys test rich?

[jbiloh]

If you care about performance, HT = Off, period.

[Defcon|Rich]

The only real difference I noticed was that you'll maintain a more steady ticrate ingame with HyperThreading Off...Does't affect the number of instances you can run or any of that garb. I remember way back having rich turn it on and off on a certain box, while we were testing stuff haha! Remember that? What a pain in the ass I was

 

The mind expands daily! Indulge

 

Howd you guys test rich?

 

 

You were our tester I think you had it changed back and forth 3-4 times..

[Defcon|Rich]

If you care about performance, HT = Off, period.

 

 

 

Care to expand on that?

[Monk]

Hyperthreading increases cache pollution.

[adamnp]

the "pollution" aspect i believe gary to be talking about here is the response time for a sleeping process that becomes ready to go from "waiting" to "executing and producing useful results"

 

The cache pollution that results from HT will clearly slow down the throughput (or amount of digital data per time unit that is delivered over a physical or logical link) on individual threads while they are figured out, especially if they're all large chunks of data. The major benefit that HT provides *IMO* is that threads can wake up and respond to sync events as well as asynch inputs more readily, and where this might benefit any "performance gameserver" has yet to be discovered

 

HT is a good idea, but the benchmarks don't prove its worthiness again, IMO

[Defcon|Rich]

Hyperthreading increases cache pollution.

 

 

Cache pollution eh? Did you learn that last year in high school?

[jbiloh]

Thats pretty rude Rich.

[Defcon|Rich]

Yes your right Jon, I apologize for being rude. I was hoping to get an explanation of your conclusion with turning off HT but received a one line opinion instead.

 

 

Adam explained it though so no worries.

 

 

 

Thanks!

[Monk]

Cache pollution eh? Did you learn that last year in high school?

 

Hyperthreading is ok for some workloads, keyword is some. Gameservers do not fall in that specific area, they mostly perform worse and/or exhibit strange behavior.

 

I have no idea where that high school comment came from, I graduated in 1998.

[Defcon|Rich]

Would it be possible HT just doesn't perform good under HL based games? We don't do a whole lot of CS so I don't have much experience with it, Other game types (UT engine etc) don't seem to care either way.

 

I know you guys do primarily HL based games which I'm assuming your experience with this is?

 

 

Thanks!

[Monk]

Perhaps, I know battlefield{1,2} servers hate HTT with big servers. CS/CSS over 24 slots with HTT on have/had major lag problems. Turning it off fixed it.

[andeelym]

This is my personal experience.

 

I have 2 dual xeons 2.4GHz servers. Using windows 2000 server (ok, flame me for using an outdated OS) i find that HT will limit the performance of instances. I can only run eg. 6 limited instances with HT on but i can run 8 instances at full potential without HT. It is like splitting each proc to 50% and have it running like its 100%.

 

Lesson learnt: Switch it off.

[gordo]

how do i turn HT off (windows xp).can it be done bye remote?

[adamnp]

It's done in the bios