Re: [Qemu-devel] [PATCH] intentinoal slowing down qemu - brake

["Manish Gajbhiye" <manish.gajbhiye@gmail.com>]

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Hi,


We are faceing one Problem in Qemu guest os winxp . The Qemu hbas been
installed in Linux CentOs 4.4 . Guest os detected the Realtek Lan Adapter .
BUt with is Adpeter we are unable  get the IP from Our Dhcp Server. Could
you suggest how to do this.

Regards
Manish


On 12/6/06, Miroslav Novak <mira@kmlinux.fjfi.cvut.cz> wrote:
>
>
>
> I'm sending some more facts that should make clear why I think the
> functionality provided by the patch is relevant. (At least for the DOS
> emulation.)
>
> Making emulated CPU slower
>   Some old DOS games runs too fast on modern CPUs, even the qemu-emulted
> ones. This patch can make these games playable.
>   The problem was reported in
> http://qemu-forum.ipi.fi/viewtopic.php?t=1264
>
> Energy saving
>   MSDOS doesn't use HLT insn. Even if the dosidle can help in command
> prompt, it doesn't work in other programs such as games.
>   This was reported in http://qemu-forum.ipi.fi/viewtopic.php?t=1372
>
> The similar approach is used in dosbox by setting "CPU cycles". I think
> qemu is better than dosbox, so it makes sense to me to include such
> capability too.
>
> This patch doesn't try to emulate the task scheduler that was why Martin
> voted against it. I'm sorry if I wasnt't clear enough in my first post.
>
> Mirek.
>
>
>
> On Thu, 30 Nov 2006, Miroslav Novak wrote:
>
> > This patch adds support for slowing down qemu and saving cpu load.
> > The '-brake' command line parameter or monitor command 'brake'
> determines how
> > long to wait in the main_loop with respect to duration of time that qemu
> used
> > for the emulation itself.
> > Thus e.g. zero value runs at full speed, 1 at 1/2 speed, 10 at 1/11
> speed,
> > etc.
> >
> > A drawback of this approach is that the timer interrupt can be missed if
> > raised too often. This happens if the loop_main divided by (1+brake) is
> less
> > than the frequency of PIC interrupts.
> > In such case the time of emulated system runs slowly.
> >
> > This problem occurs mainly for Linux emulation where kernel parameter HZ
> is of
> > several hunderds.
> > For DOS emulation, where the timer interrupts are raised usualy at 18Hz,
> this
> > approach works nice, and one can play old DOS games at reasonable speed
> and
> > save batteries.
> >
> >
> > Mirek
> >
> >
>
>
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