2018-03-30 08:56:31

by jiangyiwen

Subject: [RFC] About 9pfs support "O_DIRECT + aio"?

Hi everyone,

Currently, I found virtio-9p in VirtFS don't support "O_DIRECT + aio"
mode, both v9fs and qemu. So when user use "O_DIRECT + aio" mode and
increase iodepths, they can't get higher IOPS.

I want to know why v9fs don't implement this mode? And I will try to
implement this mode from now on.

Thanks,
Yiwen.

2018-04-02 02:48:13

by Paolo Bonzini

Subject: Re: [Qemu-devel] [RFC] About 9pfs support "O_DIRECT + aio"?

On 30/03/2018 10:53, jiangyiwen wrote:
> Currently, I found virtio-9p in VirtFS don't support "O_DIRECT + aio"
> mode, both v9fs and qemu. So when user use "O_DIRECT + aio" mode and
> increase iodepths, they can't get higher IOPS.
>
> I want to know why v9fs don't implement this mode? And I will try to
> implement this mode from now on.

Can you explain? I think 9p has support for direct I/O in Linux. See
v9fs_direct_IO in fs/9p/vfs_addr.c.

Paolo