Re: Improve performance between Network driver domain to guest OS

[Wei Liu <wei.liu2@citrix.com>]

Please don't drop Xen-devel.

On Sat, Oct 26, 2013 at 11:45:45AM +0530, shikha thakur wrote:
> Hello,
> I am not getting where to do coding for network I/O virtualization. Can you
> please give me some Documentation or any tutorial which can guide me for
> the same?
> 

A starting point would be Linux's netback / netfront drivers. You can
find them in drivers/net/xen-netback/ and drivers/net/xen-netfront.c of
Linux source tree.

Wei.

> Many thanks,
> Shikha thakur
> 
> 
> On Thu, Oct 17, 2013 at 7:07 PM, shikha thakur <srthakur26@gmail.com> wrote:
> 
> >
> >
> > ---------- Forwarded message ----------
> > From: Wei Liu <wei.liu2@citrix.com>
> > Date: Mon, Oct 14, 2013 at 3:59 PM
> > Subject: Re: [Xen-devel] Improve performance between Network driver domain
> > to guest OS
> > To: shikha thakur <srthakur26@gmail.com>
> > Cc: Wei Liu <wei.liu2@citrix.com>, George Dunlap <
> > george.dunlap@eu.citrix.com>, Ritesh Malaiya <ritesh.opensource@gmail.com>,
> > xen-devel@lists.xen.org
> >
> >
> > Please don't drop xen-devel.
> >
> > On Sun, Oct 13, 2013 at 12:12:26PM +0530, shikha thakur wrote:
> > > Hello,
> > > I apologized for the late reply.
> > >
> > > >>What's your goal? Higher throughput? Lower latency? Do you have any
> > > merit in mind?
> > >
> > > *Me: Basically higher throughput is my Aim.
> > >        **To increase the throughput, the paper i am referencing  analyzed
> > > the Xen hypervisor and got the memory latency problem.It has been
> > overcome
> > > by packet aggregation.Thus the higher throughput is achieved.With the
> > > aggregation mechanism ,the throughput almost increases linearly  with the
> > > number of VM.(As Shown in Figure below).However, It introduced delay &
> > > jitter , hence i am trying to either eliminate delay & jitter or find new
> > > way of increasing throughput.
> > >
> > > *
> > >
> >
> > I skimmed the paper. "Memory latency" seems to refer to the latency
> > introduced by memory copy. And the solution in that paper might not work
> > quite well in the scenario when a VM is expecting low latency with small
> > packets.
> >
> > >
> > > >>It depends. AIUI packet aggregation can introduce latency too. The only
> > > way to prove whether it works is to implement it.
> > >
> > >  *Me:: It has been experimented and it is introducing delay and jitter.
> > > *
> > > *First thing i wanna know, Whether the  maximize delay and jitter is
> > really
> > > a problem for higher throughput?
> >
> > Sorry I don't know. you'd better think of the system as a whole.
> > Eliminating one single bottleneck might actually decrease performance.
> >
> > > *
> > > *
> > > If yes, there are two method :-
> > > 1) Packet dimensioning tool which dynamically tune the packet
> > > aggregation.(Refer attached pdf)**
> > > 2) What i am planning to do is to imply adaptive jitter buffering
> > algorithm
> > > to dynamically tune the packet aggregation*.
> > >
> > > *If not of much trouble,Could anyone guide me which one of the above 2
> > > method is better for minimizing delay and jitter.*
> > > *
> > >
> >
> > Sorry I cannot give you a definitive answer, that's beyond my expertise.
> > I think the fun of doing research lies in the uncertainty and the thrill
> > of solving problems. If there's definitive answer to this question,
> > somebody would have done it already, right?
> >
> > The only viable way is to hack a prototype IMHO.
> >
> > Wei.
> >
> >