On Sun, Nov 03, 2013 at 09:00:54PM -0800, Eric Dumazet wrote:

On Mon, 2013-11-04 at 12:29 +0800, Herbert Xu wrote:

quoted

Have you actually measured this? The latency added by GRO is pure
processing overhead.  This is tiny when compared to the time NAPI takes
to wait.

Please take a look at 

2e71a6f8084e net: gro: selective flush of packets

This is a different problem altogether.  I was worried about the
latency in cases where we're idle and waiting for new data, while
you're worried about the latency in the CPU-bound case.

I think we can definitely improve our behaviour the CPU-bound case.
Right now if we encounter something we can't hold for GRO we
start processing it right away.  Instead we can place it in a
list for later processing together with the GRO packets.

This way GRO packets are not penalised by non-GRO packets.

You can then use the usual NAPI budget to minimise latency and
ensure scheduling fairness.

Cheers,
-- 
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
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