netdev - Re: Optimizing instruction-cache, more packets at each stage

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Message-ID: <1453135993.1223.230.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Mon, 18 Jan 2016 08:53:13 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jesper Dangaard Brouer <brouer@...hat.com>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	alexander.duyck@...il.com, alexei.starovoitov@...il.com,
	borkmann@...earbox.net, marek@...udflare.com,
	hannes@...essinduktion.org, fw@...len.de, pabeni@...hat.com,
	john.r.fastabend@...el.com
Subject: Re: Optimizing instruction-cache, more packets at each stage

On Mon, 2016-01-18 at 11:27 +0100, Jesper Dangaard Brouer wrote:

> The NAPI drivers actually already have a flush API (calling
> napi_complete_done()), BUT it does not always get invoked, e.g. if the
> driver have more work to do, and want to keep polling.
>  I'm not sure we want to delay "flushing" packets queued in the GRO
> layer for this long(?).

Since linux-3.7 we have this logic :

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=2e71a6f8084e7ac87166dd77d99c44190fb844fc


(Some arches have quite expensive high resolution timestamps)