Re: [PATCH 0/2] net: fs_enet: Remove non NAPI RX and add NAPI for TX

[leroy christophe]

Le 08/10/2014 22:03, David Miller a écrit :
> From: Christophe Leroy <christophe.leroy@xxxxxx>
> Date: Tue,  7 Oct 2014 15:04:53 +0200 (CEST)
>
> > When using a MPC8xx as a router, 'perf' shows a significant time spent in
> > fs_enet_interrupt() and fs_enet_start_xmit().
> > 'perf annotate' shows that the time spent in fs_enet_start_xmit is indeed spent
> > between spin_unlock_irqrestore() and the following instruction, hence in
> > interrupt handling. This is due to the TX complete interrupt that fires after
> > each transmitted packet.
> > This patchset first remove all non NAPI handling as NAPI has become the only
> > mode for RX, then adds NAPI for handling TX complete.
> > This improves NAT TCP throughput by 21% on MPC885 with FEC.
> >
> > Tested on MPC885 with FEC.
> >
> > [PATCH 1/2] net: fs_enet: Remove non NAPI RX
> > [PATCH 2/2] net: fs_enet: Add NAPI TX
> >
> > Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> Series applied, thanks.
>
> Any particular reason you didn't just put the TX reclaim calls into
> the existing NAPI handler?
Not really. I used the gianfar.c driver as a model.
> That's what other drivers do, because TX reclaim can make SKBs
> available for RX packet receive on the local cpu.  So generally you
> have one NAPI context that first does any pending TX reclaim, then
> polls the RX ring for new packets.
Is that a better approach ?

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