RE: [Qemu-devel] TCP_NODELAY for -redir

[Wessel, Jason]

I am in total agreement with the change. :-)

Jason. 

> -----Original Message-----
> From: 
> address@hidden 
> [mailto:address@hidden
> rg] On Behalf Of Daniel Jacobowitz
> Sent: Thursday, November 16, 2006 8:44 PM
> To: address@hidden
> Subject: Re: [Qemu-devel] TCP_NODELAY for -redir
> 
> On Mon, Nov 13, 2006 at 02:30:27PM -0500, Daniel Jacobowitz wrote:
> > I was trying to run GDB remote debug tests through a -redir socket 
> > today.  It crawled unbelievably.  Paul guessed that slirp 
> wasn't using 
> > TCP_NODELAY, and Nagle was to blame.
> > 
> > He was even righter than usual.  Adding TCP_NODELAY speeds up this 
> > particular workload by (very approximately) 54x.  See 
> trivial attached 
> > patch.
> > 
> > Is this going to bite other things, i.e. does it need to be 
> > configurable?
> 
> No comments on this...
> 
> My reasoning, by the way, was that slirp is being used as a 
> TCP-to-TCP gateway.  I think that if we were to use nagle 
> here, we'd end up doing it twice: once at the sender inside 
> the guest, and once again on the host's TCP stack.  Using 
> TCP_NODELAY lets the guest take responsibility.
> 
> 
> --
> Daniel Jacobowitz
> CodeSourcery
> 
> 
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