Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi virtqueue support

[Paolo Bonzini]

Il 13/08/2014 12:19, Ming Lei ha scritto:
>> > The problem is that your patches to do touch too much code and subtly
>> > break too much stuff.  The one I wrote does have a little breakage
> Could you give a hint about which stuff are broken? Last time, you mention
> virtio-scsi need to keep AIOCB live after returning, I have fixed it in V1.

They are dataplane-specific, while there's no reason not to have the
same benefits elsewhere.  They are file-specific, while there's no
reason not to have the same benefits for e.g. iSCSI (though iSCSI now
uses coroutines instead of bdrv_aio_*).  They touch AioContext for no
reason, and introduce a bunch of layering violations everywhere.

They are simply the wrong API.

>> > because I don't understand bs->growable 100% and I didn't really put
>> > much effort into it (my deadline being basically "be done as soon as the
>> > shower is free"), and it is ugly as hell, _but_ it should be compatible
>> > with the way the block layer works.
> I will take a careful look to your patch later.
> 
> If coroutine is still there, I think it still can slow down performance.

No, it's not there.  Please try the patch.

Paolo