Regards, Jim Kenzig http://thin.net
Hyperthreading (HT) creates a real moral problem for me, even on Windows
It has obvious performance advantages that you can easily see on an HT aware operating system. BUT, when you get to a scenario where a system is doing a serious amount of work, things can fall apart a lot faster on an HT system than on a non-HT system.
So HT gives me a significant advantage at low to medium levels of CPU utilization, but when things max out I'd rather not be running HT because it starts falling apart. It's a bit like the redline on a tacho, stay below the redline and life's sweet, go above and things could blow.
So you have to be a bit pragmatic.
Scale your TS systems so they won't hit the wall and you get all the
advantages of HT with no problems. When things start getting too busy,
add more servers. Some sort of CPU limitting software (TMULimit,
Appsense performance suite, Tscale/Expedian, Armtech, Threadmaster) to
control runaway threads is absolutely mandatory if you want a quiet life
On file/print servers (2003) I've had some really painful personal
experience about what can happen with HT when a server (2003 cluster)
gets too busy. I'd really rather take a 10-20% dip in performance than
have a file server cut out on me unexpectedly, hanging all the TS
But if you scale things properly and be careful about tuning antivirus settings etc, and add extra capacity when it's needed, you can benefit from HT at minimal risk.
Volante Systems Ltd
18 Heussler Terrace, Milton 4064 Queensland Australia. Ph: +61 7 3246 7704 email: rmack@xxxxxxxxxxxxxx web: www.volante.com.au
-----Original Message----- From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of Tim Mangan Sent: Friday, 1 October 2004 8:04 AM To: thin@xxxxxxxxxxxxx Subject: [THIN] Re: Hyperthreading
I did a lot of testing with it last year. I never saw it cause an
error, but things often stall due to the idle processing clearing out
too much on the chip when one of the logical processor idles. It caused
erratic performance. Under a heavy load it *might* cause a crash, but I
never saw one. I would definitely disable HT under 2000.
-----Original Message----- From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of Bob Sent: Thursday, September 30, 2004 9:50 AM To: thin@xxxxxxxxxxxxx Subject: [THIN] Hyperthreading
Has anybody experimented with Hyperthreading On -vs- Off on Win2k servers? I've heard rumblings that it can be problematic, and perhaps decrease performance. I noticed that most SpecInt. winners have it disabled. I'm considering disabling it on one of my farm servers to observe the results. If anybody else has experimented I'd love to hear about it.
Thanks in advance,