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

[Aurelien Jarno <aurelien@aurel32.net>]

Jan Kiszka a écrit :
> On 2011-02-08 09:08, Paolo Bonzini wrote:
>> On 02/08/2011 08:26 AM, Aurelien Jarno wrote:
>>> I forget to remember when we decided that AIO should be implemented on
>>> any host OS. Any pointer?
>> To be fair, I/O-heavy workloads are almost unusable without AIO.  For 
>> Window targets, they also crash under SMP due to the Windows AP 
>> watchdog.  But then TCG and SMP do not go very well together anyway.
>>
>> However, I think deprecating Win32 support would be a very bad idea.
> 
> It would be too early at this point.
> 
> But if Windows is once the only reason to keep tons of hardly tested
> code paths around or to invest significant additional effort to change
> logic or interfaces in this area, than I would prefer that step. I'm
> hacking on IOTHREAD vs. !IOTHREAD for some weeks now, and all those
> subtle differences are really a PITA and source of various breakages.
> 
> People interested in that platform should finally realize that its fate
> is coupled to reducing the #ifdefs as well as the design differences we
> see right now and even more in the future.
> 

The guilty here is IOTHREAD. Windows support predates IOTHREAD concept,
it's just that people who introduce IOTHREAD didn't care about Windows
support at all and added these #ifdef. Disabling Windows support because
of that is not fair.

We should probably get rid of KVM support in QEMU, so if someone has an
idea for a cool TCG feature that can't be supported in KVM, it's the
moment to submit it. We can add it with #ifdef, and in one year just ask
for KVM support removal.

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