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Date: Tue, 20 Jan 2009 22:29:10 +0100
From: Stefan Weil <weil@mail.berlios.de>
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Subject: Re: [Qemu-devel] Re: Extremely slow graphic updates
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To: qemu-devel@nongnu.org

Paul Brook schrieb:
>> What is the quickest way for me to reproduce this problem?
>> Have you seen this on ppc emulation only?
>>
>> I gather that the guest is in text mode. Have you seen this in graphical
>> mode too? If yes, what was the resolution of the guest?
>>     
>
> Steps to reproduce:
> - Start qemu (doesn't matter which target or guest OS).
> - Press c-a-2 to switch to the monitor.
> - type "help<enter>"
> - Watch the output slowly appear over the next 30 seconds
>
> Running qemu over a forwarded X connection from a different machine (i.e. 
> ssh -X) suffers a marked slowdown. With this configuration the early x86 boot 
> stages are visibly much slower, in addition to the virtual console slowness 
> mentioned above.
>
> The monitor virtual console, VGA text mode and the graphical mode used by the 
> knoppix bootloader[1] all show marked slowdown. It's unclear whether 
> truecolor modes are effected.
>
> [1] I'm guessing this is either VGA 16 color or VESA 256 color mode.
>
>   

I see a similar effect with the first serial console: booting a mips malta
linux kernel with debug output and a serial console took 15 s (up to
start of devfs),
now it takes 140 s with local SDL (estimated baud rate 600 or 1200 baud).
The serial console is only slow when it is selected.

VNC output or -nographic output is still fast.

Regards
Stefan Weil