Re: [Qemu-devel] [RFC] Replace posix-aio with custom thread pool

[Anthony Liguori <anthony@codemonkey.ws>]

Andrea Arcangeli wrote:
> On Fri, Dec 12, 2008 at 12:54:21PM +0100, Jens Axboe wrote:
>   
> In the meantime I think it'd be better to -EINVAL (so the userland
> thread can fallback to userland thread pool) instead of just behaving
> synchronously that can break GUI and interactive behavior...
>   

Yes, IMHO, this is the major problem with the current state of 
linux-aio.  I really don't want to expose an aio= flag for users to 
configure.  I'd rather just do the Right Thing automatically.

>> I added CLONE_IO some time ago to avoid that, so it's perfectly possible
>> to share cfq io contexts with threads or processes even in userspace!
>>     
>
> It's available in recent kernels I see! so the fix is easy. Only
> problem is how to pass CLONE_IO to pthread_create... We'll have to
> make a linux-only change and call clone by hand under some #ifdef
> CLONE_IO.
>   

I have no problem with this and I believe Chris was going to attempt an 
implementation.

Regards,

Anthony Liguori

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