How to adjust VM's speed ? Like "transmission gear"

[vmvmvm626]

I want to adjust VM's speed , not to speed up VM.

For example , Slow down the VM , when 1 minute has passed in the real world , only 30 seconds have passed in VM.

So , how can I make that ?

[admin]

Please confirm which OS are you using ......

Regards,

Randhir

[vmvmvm626]

ubuntu , centos ,suse……

[vmvmvm626]

Anyone can help?

[daphnissov]

Can you better explain what you're trying to achieve? I don't understand really what you wish to accomplish.

[vmvmvm626]

Indeed , I want to slow down the time speed of VM , in order to make the VM's time goes slower then the real time.

For example , it‘s’ 10:00:00 o'clock ,both your clock and VM's clock . Wait a minute . Now your clock shows 10:01:00 ,and VM's clock shows 10:00:30. I need this effect.

.

[daphnissov]

There is no way of which I'm aware to produce such an effect. What is your use case for such an odd request, if I may ask?

[vmvmvm626]

I want to observe and measure network behavior of OS. But it sends packet too fast . So I have to slow down the OS .

As we know , it is almost impossible for Physical host . Maybe VM can ?

[daphnissov]

That's what packet capture tools are for. You'll have to capture the behavior you wish to analyze and then step through it manually.

[vmvmvm626]

Packet capture tools can do this, but I want to tamper the packet with my app . Now I need to debug my app to find some error .

You know ,if I debug my app with single step, the tcp link which is sending packets will be disconnected because of overtime.

So this won't happen ,if the VM does not 'feel' the debug time. For example , I have single step debug my app for 5seconds ,if VM feels only 5 millisecond passed ,the link won't be disconnected.

[daphnissov]

In that case, you either need to use an injector or a packet capture and replay tool. One I know of is tcpreplay (Tcpreplay). As long as you capture in libpcap format you should be able to alter the data and replay it.

[vmvmvm626]

Replay tool may not help. My app can influence the behavior of tcp .Replay tool can't Interact with my app ,because it won't change the behavior of tcp ,it only acts as what it has recorded before.

[vmvmvm626]

Anyone can help?Please

[Dave_the_Wave]

Time Dilation and Lag are often addressed issues in video game servers, and if anyone knows how to simulate that, it will be among the developers those realms.

[vmvmvm626]

Very agree . I thought everything of VM ,include its timer, could be developped . 

VM gets the cycle rate of the processor clock from vsphere . So vsphere can give VM a Arbitrary value of the cycle rate in theory  to make VM‘s timer go  faster or slower.

[vmvmvm626]

Anyone can help? help

[vmvmvm626]

Any expert ？help！