RE: [ofa-general] Re: [PATCH RFC] RDMA/CMA: Allocate PS_TCPportsfrom the host TCP port space.

Felix Marti
2007-08-20T01:47:10Z

> -----Original Message-----
> From: ak@suse.de [mailto:ak@suse.de] On Behalf Of Andi Kleen
> Sent: Sunday, August 19, 2007 4:28 PM
> To: Felix Marti
> Cc: David Miller; jeff@garzik.org; netdev@vger.kernel.org;
> rdreier@cisco.com; linux-kernel@vger.kernel.org;
> general@lists.openfabrics.org
> Subject: Re: [ofa-general] Re: [PATCH RFC] RDMA/CMA: Allocate
> PS_TCPportsfrom the host TCP port space.
>
> "Felix Marti" <felix@chelsio.com> writes:
>
> > what benefits does the TSO infrastructure give the
> > non-TSO capable devices?
>
> It improves performance on software queueing devices between guests
> and hypervisors. This is a more and more important application these
> days. Even when the system running the Hypervisor has a non TSO
> capable device in the end it'll still save CPU cycles this way. Right
> now
> virtualized IO tends to much more CPU intensive than direct IO so any
> help it can get is beneficial.
>
> It also makes loopback faster, although given that's probably not that
> useful.
>
> And a lot of the "TSO infrastructure" was needed for zero copy TX
> anyways,
> which benefits most reasonable modern NICs (anything with hardware
> checksumming)
Hi Andi, yes, you're right. I should have chosen my example more
carefully.

>
> -Andi