explorer.exe - only single threaded

[Bossk128]

I've a dual core system. When I first load up Windows XP, inspecting explorer.exe in Task Manager shows it has affinity for both cores. If I open Explorer to browse files, and inspect the exporer.exe process again, it's jumped down to affinity on one core only. This has the effect of not applying dual core affinity to my apps loaded by explorer.exe i.e., the Start Menu- invariably this is all of my apps, resulting in an OS that doesn't seem to be able correctly to use dual core aware apps (for instance, Unreal Tournament 3, or Orthos).

Can anyone let me know how I can tell what is telling explorer.exe to use only one core?

Thanks in advance.

 

[NathanE]

That's not standard behaviour for Explorer on XP. It should have the affinity set to both cores of that CPU. Although whether XP's Explorer will actually make significant use of multi-threading is another matter. Is it possible you have installed one of those crappy freeware programs that control the affinity of running processes? If so I would recommend uninstalling it.

Please note that Explorer is just the "look and feel" for Windows and doesn't actually control other applications in terms of threading. UT3 is a multi-threaded game so when playing that if you Alt+Tab out and check Task Manager you should see that both cores of your CPU are quite heavily loaded.

 

[Bossk128]

Thanks for the quick response.

I know this isn't how explorer should work- that's why I want to fix it! It does tend to have dual affinity on boot (before I open up Explorer as an application that is), but after some minutes (I've no idea when) it reverts to single threaded.

I've no software installed to control affinity.

As far as Explorer not influencing other apps, I've been led to believe differently. Any application started by explorer.exe will inherit it's affinity, and as the Start menu is Explorer, any .exe I start via the Explorer window/My Computer/Start-Run, or the Start menu proper, it also is only single threaded.
I've experimented with Orthos- if explorer.exe is single threaded, Orthos errors on startup with an 'affinity mask' error (I forget the actual text I'm afraid) and only stresses one core. If I then set Explorer to to have affinity on both cores, and start up Orthos, the error goes and both cores are stressed. This is repeatable, and also works with UT3 (in fact, UT3 performance is what let me find this problem in the first place).

It's absolutely doing my head in, because I'm not sure if Windows would perform better if explorer kept affinity properly. It's a pest to check out the process whenever I weant to play a game too.

 

[NathanE]

Ah yes I forgot about the affinity inheritence that occurs for any application that Explorer starts up. I can see now how that is a major problem for you

I'm not sure what could be causing Explorer to have that broken affinity. Have you checked your startup applications for anything rogue using Sysinternals Autoruns?

 

[Bossk128]

Ah yes I forgot about the affinity inheritence that occurs for any application that Explorer starts up. I can see now how that is a major problem for you

I'm not sure what could be causing Explorer to have that broken affinity. Have you checked your startup applications for anything rogue using Sysinternals Autoruns?

I haven't- I've checked using MSconfig, and it all seems fine. But autoruns is a tool I haven't seen before- I'll give that a shot, thanks.

I've also read about other unrelated explorer problems that point to dodgy dll plugins (broken avi files being the major one). I'm going to try to see if I can find a tool to inspect which apps have plugged into Explorer (off the top of my head, things like 7-Zip, although as it's dual core aware, it should be fine). I don't suppose Autoruns does this, does it?

Plenty of time to research as I'm at work today- it's like a graveyard. I'll have a look tonight. Thanks again Nathan.

Edit: I've had a wee browse of the sysinternals website- what a great collection of tools. I've never heard of them before. Looks like Autoruns will inspect the DLLs starting upwith explorer.exe. Thanks.

 

[Bossk128]

OK, after uninstalling all the apps that Autoruns told me hook into Explorer, I finally uncovered which one it was- the last one to uninstall, of course!!

7Zip was fine, WinAce was fine, ATI Catalyst was fine (may not reinstall that one), Alcohol 120% was fine......

The culprit seemed to be Notmad Explorer, my 3rd party digital audio player manager from RedChairSoft. After removing that and rebooting, my explorer.exe kept affinity to both cores no matter what I was doing. I'm going to see if I can get Notmad Explorer to work though, because it's a good piece of software. I've reinstalled all my other software except Alcohol 120% so far, and it looks good.

Thanks for your help.

Bossk128

 

[NathanE]

Knew it would be some dodgy rogue application doing it. Some developers just don't have a clue what they are doing! :/