Re: [Qemu-devel] Re: [PATCH 0/3] Refactor AIO to allow multiple AIO implementations

[Anthony Liguori]

Ryan Harper wrote:
> * Anthony Liguori <address@hidden> [2008-09-22 22:44]:
>   
> > Can you run the same performance tests with the following patches (using 
> > sync=on instead of cache=off)?
> >
> > You'll need my aio_init fix too.  I suspect this will give equally good 
> > performance to your patch set.  That's not saying your patch set isn't 
> > useful, but I would like to get performance to be better for the case 
> > that we're going through the page cache.
> >     
>
> I can run the test, but it is orthogonal to the patchset which is
> focused on using O_DIRECT and linux-aio.
>   

Yes, I'm trying to understand where the performance is coming from.  The 
hunch is that supporting multiple simultaneous requests along is what 
did it.  O_SYNC should give similar completion behavior to O_DIRECT.

Regards,

Anthony Liguori