Re: Fast usermode networking with QEMU

[Stefano Brivio]

Hi Anders,

On Mon, 23 May 2022 14:51:17 -0600
"Anders Pitman" <anders@apitman.com> wrote:

> I came across this blog post[0] concerning passt, which is an
> alternative usermode networking implementation for QEMU.

...and I just came across your email, entirely by chance. I'm not
actively monitoring this list most of the time.

> I'm working on a project that uses QEMU on Windows hosts running
> Linux guests. I'm trying to get faster usermode networking than is
> available with libslirp. My performance target is 200Mbps even on
> older or less powerful hardware, such as Celeron mini PCs. Currently
> I'm seeing 15-30MBps with libslirp.
> 
> It appears that passt doesn't currently support Windows, correct? Is
> there a guess as to how difficult that might be to implement? If the
> speedup is significant, I would be interested in taking a crack at
> adding Windows support.

I gave some quick comments about the challenges I see in the
perspective of a FreeBSD port at:
  https://bugs.passt.top/show_bug.cgi?id=6#c2

and I suppose a Windows port, by the way tracked at:
  https://bugs.passt.top/show_bug.cgi?id=8

could face similar challenges.

But from a quick browsing of the Winsock reference documentation months
ago, it actually looked easier because there seemed to be a description
of an equivalent for every bit of TCP socket information we're fetching
on Linux via TCP_INFO socket option.

I can try to remember/double check and give more details if it helps,
but if you're familiar with Windows development I suppose I wouldn't add
much value. :)

-- 
Stefano