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

[OHMURA Kei <ohmura.kei@lab.ntt.co.jp>]

>>> "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.


By the way, the following data is a result of x86 measured in QEMU/KVM.  

This data shows, how many times the function is called (#called), runtime of 
original function(orig.), runtime of this patch(patch), speedup ratio (ratio).

Test1: Guest OS read 3GB file, which is bigger than memory.
#called     orig.(msec)     patch(msec)     ratio
108         1.1             0.1             7.6
102         1.0             0.1             6.8
132         1.6             0.2             7.1
 
Test2: Guest OS read/write 3GB file, which is bigger than memory.
#called     orig.(msec)     patch(msec)     ratio
2394        33              7.7             4.3
2100        29              7.1             4.1
2832        40              9.9             4.0