Interesting MP Server Hosting Bug/Issue

Velusion · #1 February 23rd, 2007, 03:43 PM

I host a number of games on a VMware virtual machine hosted on VMware server. I�m familiar with VMware platform as I manage a VMware cluster at the datacenter I work at. I�ve never had any issues with VMware until now.

Basically the VMware guest that runs the games started to act up when I upgraded the host to an AMD dual-core system. The time on both the OS and the game would go about 2x faster than normal. After lots of research I found out there is an AMD patch that addresses the issue� sure enough I installed it and the OS and other applications on the server started to work fine (though it still gains a minute a day � nothing a simple time synch program can�t fix).

I assumed the problem went away in my dom3 games as well as I didn�t notice any drastic time changes there either. However, the timekeeping issue didn�t disappear with Dom3 is just got better. Now, instead of time going 2x as fast it goes about 1.175x as fast. So hence if I set the Dom3 timer to host a turn in 24 hours, time in Dom3 will speed up and host the game in approximately 21.5 hours. Not huge, but still unacceptable.

So my question � why is Dom3 the only application/game that still messes up? How does the server track time? Do the Devs or other knowledgeable people have any suggestions on how to fix this? I assume Dom3 looks to the hardware in some way for timekeeping and ignores the OS� (wah!).

Currently with the game I am going to just increase the hosting time. This isn�t a permanent fix as it is confusing though. I have a laptop I don�t really use anymore that I�ll setup to do the hosting, but I dislike the thought of an extra physical machine with I have processing power still available to use on an existing machine (habit I suppose).

Any suggestions would be welcome� otherwise let this server as a warning to anyone planning to host games on a virtual machine as I did�

Gandalf Parker · #2 February 23rd, 2007, 07:45 PM

Hmmm Im trying to remember who our AMD tester was.
I will forward this.

Oh yeah, stupid madatory customer support irritating question (we will stop asking if your computer is plugged in when it stops being an answer to some peoples problems)....
Is amd64 appropriate to your machine? and have you verified that the dom3 link in the path links up to the file dom3_amd64 in the install directory?

Gandalf Parker

Velusion · #3 February 23rd, 2007, 08:01 PM

Quote:

Gandalf Parker said:
Oh yeah, stupid madatory customer support irritating question (we will stop asking if your computer is plugged in when it stops being an answer to some peoples problems)....
Is amd64 appropriate to your machine? and have you verified that the dom3 link in the path links up to the file dom3_amd64 in the install directory?

Gandalf Parker

I'm not running a 64bit OS and I don't have a a dom3_amd64 in the install folder anywhere where I can see....

The processor supports 64bit and is a dual-core, but I'm running the 32bit windows server OS on the guest.

PvK · #4 February 23rd, 2007, 08:45 PM

I tested it on two (sperate, non-dual) AMD systems:
1.4 GHz Athlon Thunderbird
AMD Athlon(tm) XP 2100+, ~1.7GHz

But running Win 98SE and Win2KPro (respectively) natively, not using VMWare. No problems to report in general. But I also did not test the server timer for accuracy versus real-world time.

PvK

Velusion · #5 February 23rd, 2007, 09:10 PM

Well you have to keep in mind that the actual hardware running the Dom3 game is virtual hardware provided by VMware. Everything is emulated... so unless it was tested on a Virtual Machine, it won't matter.

PvK · #6 February 23rd, 2007, 09:32 PM

Yes. I don't know of anyone but you having tested it on a virtual machine.

lch · #7 February 23rd, 2007, 09:48 PM

Seems to be an issue with VMware, not the server per se. Have you tried googling for "vmware timekeeping"? The first two hits are some technical whitepaper which I didn't bother to open (bah, PDF), the third and fourth (one for Windows, one for Linux) titled "Host Power Management Causes Problems with Guest Timekeeping" has some info and links and something that seems to be a possible workaround.

Gandalf Parker · #8 February 23rd, 2007, 09:54 PM

Hmmm my install only shows these executables.
dom3_amd64
dom3_ppc
dom3_x86
and the Windows install creates a dom3.exe

On my server (Debian Linux on an x86) the install properly recognized the system and then linked the actual dom3 command to the dom3_x86 executable. If you are AMD but not 64 then Im not sure what it would choose.

Velusion · #9 February 23rd, 2007, 09:57 PM

Oh yea... I spent hours going through the white papers, etc. Most of the timekeeping issues involve the clock going slower... only a few talk about it going faster, and I tried those fixes. After lots of research I came upon the AMD dual-core windows patch - and that fixed it with the OS.

I don't know what Dom3 is looking at when it keeps time, so I'm not sure whose fault it is really. Probably VMwares or AMD... unless Dom3 keeps track of time in some non-standard way. It certianly doesn't sync up with the OS (which makes sense).

lch · #10 February 24th, 2007, 08:48 AM

Just checking, so you have tried to finetune your settings manually like described in point 3 in that web page?

Quote:

Edit config.ini, adding the lines described below.

The example presented here assumes that the host computer has a maximum speed of 1700MHz. The first line is the most important one. It should be your host computer's maximum speed in KHz�that is, its speed in MHz times 1000, or its speed in GHz times 1000000.

host.cpukHz = "1700000"

host.noTSC = "TRUE"

ptsc.noTSC = "TRUE"

The second and third lines enable a mechanism that tries to keep the guest clock accurate even when the time stamp counter (TSC) is slow.