Re: [Qemu-devel] Re: [PATCH 2/7] Enable I/O thread and VNC threads by default

[Aurelien Jarno]

Aurelien Jarno a écrit :
> Paolo Bonzini a écrit :
>> On 02/08/2011 12:15 PM, Aurelien Jarno wrote:
>>> however
>>> it should not be done ignoring all the*current*  drawbacks of the
>>> iothread mode. We know them (at least for some of them), so let's try to
>>> solve them.
>> Let's also enumerate them.
>>
> 
> From what I know:
> - performance regression in TCG mode

I setup an x86_64 guest on an x86_64 host (Intel Xeon E5345). Nothing
was running except the standard daemons and the CPU governor was set to
"performance" on all CPU. I then compared the network performance using
netperf in default mode, through a tap interface and a virtio nic. I got
the following results (quite reproducible, std below 0.5):
- without IO thread: 107.36 MB/s
- with IO thread:     89.93 MB/s

I haven't redone the tests I have done two weeks ago on MIPS, ARM,
PowerPC and SH4 (using different emulated network cards: smc91c111,
rtl8139, e1000, virtio), but it was roughly the same slow down, except
on ARM where it was more important.

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net