HT and Software incompatibilities

[wahorger]

I've just gotten an 865 motherboard, installed XP, and have found some software does not appear to "play nice" when HT is turned on. I have found the following software packages show signs of severe distress (or just stop working) and will describe what happens. Any help or insight would be useful.

1. Firefox 1.0 (and 1.0.1): Application will freeze (not respond) for periods from < 1 sec to over 30 seconds, randomly (usually at least twice per minute), more readily when scrolling vertically in a document. Setting processor affinity to 1 or uniprocessor at the application will allow Firefox to work fine (apparently).

2. Abobe PhotoShop 6.0 and 7.0: When exiting the application, the window(s) will not close, and Task Manager will show the application as consuming lot of CPU (> 15 %). Have to either force a reboot or a logout, or multiple "End Task" selections. Occurs every time HT is on and processor affinity is un-set. Turning HT off solves the problem, or setting uniprocessor affinity.

3. Eudora V6.0.2: Same bahavior as PhotoShop, but more sporadic. Usually, it'll work fine.

4. Anecdotal only: I've had a few installer programs "act funny", but can't put my finger on the precise nature of the failure/issue they were having.

Of all the applications I use, these are the only ones where I can see and quantify the effect of HT in a negative way. For all other apps, the HT seems not to interfere with the operations.

Any ideas on why these particular apps might be susceptible? Running with HT turned ON is certainly preferable - things are a lot faster with HT!

Thanks, Bill

[ClayB]

Bill -

I don't have any specific solutions or advice. Have you tried asking the software producers if they know of any specific problems interacting with HT?

As a guess, I would think there might be some thread priority issues. On HT systems, the OS sees two full processors when there really only is the one. Thus, it believes it can schedule lower-priority threads (which it would not do on a single non-HT processor) more frequently and, since resources are shared on HT processors, the lower-priority thread leaches cycles from the main thread.

While we've seen this phenomenon with some applications, I don't recall any of the ones you listed. Setting the process affinity negates the OS option of having two (logical) processors to schedule threads onto. Even so, other processes could be scheduled on the "extra" processor and still show some performance benefit to the overall system.

--clay

[gopalraichur]

Similar problem here. Got a new box for our server, 865GVHZ mobo, 3Ghz HT processor and 512 MB ram. everything was running fine till i installed firefox. The app used to freeze randomly for a couple of seconds. i found a quick way to un-freeze was to start the task manager. then this behaviour was seen with IE too and then with Visual Studio. One thing i noticed when working on VS was that during the time the app was frozen, the task manager showed two instances of the app with the status as 'not responding'. i suspected this to be something to do with HT. On disabling it all is fine, no freezes whatsoever. Am running with HT turned off, but need to know if there is any solution ...

OS is WinXP SP2 with all latest updates.

Apps working fine with HT on
IIS with PHP, serves pages nicely !
Mercury32 works fine too
PSP 7 too is ok
Irfanview32
Nero Express
Thunderbird (not tested much)

Apps mis-behaving with HT on
Firefox 1.0.2
IE 6.0 sp2
Visual Studio 6.0

- Gopal

[wahorger]

I apologize for not posting this before.

On the Mozilla forum, I had posted a question about this, and metioned that setting the affinity to 1 processor on the executable seemed to solve the issue. A couple of weeks ago, someone posted another reply, recommending that a BIOS update might be in order; seems that some BIOS'es are not HT compatible, or have minor tweaks needed to support HT.

Since I had an Intel branded board, I thought this was kinda strange, but did re-flash the BIOS (by the way, it goes so smooth with the software supplied - never had that ease of installation before), and re-tested the known problem applications. Flawless, no problems, and much faster execution of processor intensive sections.

I am a "happy camper".

Hope this helps,
Bill

[gopalraichur]

It sure helped !
A BIOS update did the trick !

Everything is working fine now, no hiccups with any application and HT is enabled.

Thank you very much
Gopal

[ClayB]

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wahorger@yahoo.com wrote:

Since I had an Intel branded board, I thought this was kinda strange, but did re-flash the BIOS (by the way, it goes so smooth with the software supplied - never had that ease of installation before), and re-tested the known problem applications. Flawless, no problems, and much faster execution of processor intensive sections.

I am a "happy camper".

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Bill -

Glad things haveworked out for you with this. I guess the thing to first recommend whenever we get an HT problem in the Threading Forum is to suggest a BIOS upgrade.

Thanks for the information and testimonial.

--clay