[dpdk-dev] [PATCH v1] ixgbe_pmd: forbid tx_rs_thresh above 1 for all NICs but 82598
Ananyev, Konstantin
konstantin.ananyev at intel.com
Fri Sep 11 19:42:48 CEST 2015
> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Matthew Hall
> Sent: Friday, September 11, 2015 6:18 PM
> To: Vladislav Zolotarov
> Cc: dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v1] ixgbe_pmd: forbid tx_rs_thresh above 1 for all NICs but 82598
>
> On Fri, Sep 11, 2015 at 07:18:20PM +0300, Vladislav Zolotarov wrote:
> > We thought about linearization too. It's doable with extra mempool and it
> > may be optional so that those that don't need could compile it out and/or
> > disable it in a runtime...
>
> High-level question. How realistic is sending a 40-segment frame in the first
> place? This whole thing seems kind of academic to me unless I missed
> something.
>
> I usually use 2K pktmbufs and I don't think this is an uncommon size. Most
> jumbo frame hardware only does 9.5KB max frame size or so.
>
> So I am having a hard time imagining how I'd end up with more than 10 segments
> as a worst-case scenario.
As I remember, with freebsd stack when TSO is on it was not unusual to see chains of ~30 segments.
That's over port with 'normal' mtu (1.5K).
Konstantin
>
> Matthew.
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