Re: [Qemu-devel] Re: [PATCH v2] qemu-kvm: Speed up of the dirty-bitmap-traveling

[Alexander Graf]

On 17.02.2010, at 10:47, Avi Kivity wrote:

> On 02/17/2010 11:42 AM, OHMURA Kei wrote:
>>>>> "We think"? I mean - yes, I think so too. But have you actually measured 
>>>>> it?
>>>>> How much improvement are we talking here?
>>>>> Is it still faster when a bswap is involved?
>>>> Thanks for pointing out.
>>>> I will post the data for x86 later.
>>>> However, I don't have a test environment to check the impact of bswap.
>>>> Would you please measure the run time between the following section if 
>>>> possible?
>>> 
>>> It'd make more sense to have a real stand alone test program, no?
>>> I can try to write one today, but I have some really nasty important bugs 
>>> to fix first.
>> 
>> 
>> OK.  I will prepare a test code with sample data.  Since I found a ppc 
>> machine around, I will run the code and post the results of
>> x86 and ppc.
>> 
> 
> I've applied the patch - I think the x86 results justify it, and I'll be very 
> surprised if ppc doesn't show a similar gain.  Skipping 7 memory accesses and 
> 7 tests must be a win.

Sounds good to me. I don't assume bswap to be horribly slow either. Just want 
to be sure.


Alex