Re: Re: [Qemu-devel] FC2 guest is working slower than RH9 on FC2 host

[Mulyadi Santosa <a_mulyadi@softhome.net>]

On Tuesday 02 August 2005 13:26, Mulyadi Santosa wrote:
> I have tried it....still feel slower than RH 9....I've tried
> HPET=disable too with no luck. I'll try to investigate this issue
> deeper but still welcome everyone's ideas

Following up my own earlier posting today, I have discovered the reason 
why FC2 boots and runs so slow. FC2 default kernel is incorporating non 
standard 4G/4G VM split, enabled by this .config parameter:
	CONFIG_X86_4G_VM_LAYOUT=y

It has been warned already by Linux kernel's help related to the above 
parameter, that it triggers more TLB flushes and more overhead when 
doing copy_from/to_user. Qemu-doc.html also warns more or less same 
thing about FC2 default kernel

So far, the best I can tell is, use standard 2.6 kernel on both host and 
guest to avoid this kind of non standard VM split. clock=pit also helps 
speeding up execution a bit

regards

Mulyadi