qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] Speed menu for GTK interfaace


From: Programmingkid
Subject: Re: [Qemu-devel] Speed menu for GTK interfaace
Date: Wed, 4 Jan 2017 10:43:46 -0500

On Jan 4, 2017, at 3:37 AM, Gerd Hoffmann wrote:

>  Hi,
> 
>> It is quite simple, there would be a 100% to a 1% menu item. It would look 
>> like
>> this:
>> 
>> Speed
>> -------
>> 100%
>> 90%
>> 80%
>> 70%
>> 60%
>> 50%
>> 40%
>> 30%
>> 20%
>> 10%
>> 1%
>> 
>> 
>> Each menu item would call cpu_throttle_set(). The value sent to this 
>> function would
>> be determined like this:
>> speed = -1 * menu_number + 100;
> 
> ok, that is the info I was looking for.
> 
>> speed would be sent to the cpu_throttle_set() function. This function would 
>> reduce
>> the CPU usage of QEMU on the host. 
>> 
>> Why would someone want to slow down QEMU?
>> - The user is using a laptop and don't want it to heat up.
> 
> Sort-of makes sense, to keep the laptop quiet.
> 
>> - The user wants to slow down a video game that is a little too challenging.
> 
> Sure this would work?  Throttling isn't a smooth slowdown, the cpu
> continues to run at full speed and is forced to pause now and then.
> 
>> - The user wants to save energy.
> 
> Pointless.  Laptop may run longer, but your job needs more time to
> complete too.  And constant vcpu start/stop isn't good to save power,
> the cpus can't enter deep sleep states then because of the frequent
> wakeups.
> 
>> - The user wants to conduct some kind of stress test on a program and see how
>> it handles under low cpu resources. 
> 
> Makes sense too.
> 
> We already have "pause" in gtk, adding a "throttle" item next to it
> looks reasonable to me.  I don't think it is that useful to have 10%
> steps in there, you probably never throttle 10% in practice.  It's
> probably more useful to have something like "throttle -> off / 50% /
> 90% / 95% / 99%".

Actually the 10% one is the one I use the most. I use it when I have to
test code in OpenBIOS. I wouldn't mind adding a 95% menu item.




reply via email to

[Prev in Thread] Current Thread [Next in Thread]