Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?

[Alexander Graf]

On 04.08.2010, at 18:54, Avi Kivity wrote:

> On 08/04/2010 07:45 PM, Alexander Graf wrote:
>> 
>> I see two alternatives out of this mess:
>> 
>> 1) Speed up string PIO so we're actually fast again.
> 
> Certainly, the best option given that it needs no new interfaces, and 
> improves the most workloads.
> 
>> 2) Using a different interface (that could also be DMA fw_cfg - remember, 
>> we're on a private interface anyways)
> 
> A guest/host interface is not private.

fw_cfg is as private as it gets with host/guest interfaces. It's about as close 
as CPU specific MSRs or SMC chips.

> 
>> Admittedly 1 would also help in more cases than just booting with -kernel 
>> and -initrd, but if that won't get us to acceptable levels (and yes, 8 
>> seconds for 100MB is unacceptable) I don't see any way around 2.
> 
> 3) don't use -kernel for 100MB or more.  It's not the right tool.

Why not? You're the one always ranting about caring about users. Now you get at 
least 3 users from the Qemu development community actually using a feature and 
you just claim it's wrong? Please, we've added way more useless features for 
worse reasons.


Alex