netdev - Re: [PATCH 2/2 net-next] net: move qdisc ingress filtering code where it belongs

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Date:	Mon, 11 May 2015 16:30:38 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alexei Starovoitov <ast@...mgrid.com>
Cc:	Pablo Neira Ayuso <pablo@...filter.org>,
	Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
	davem@...emloft.net, jhs@...atatu.com
Subject: Re: [PATCH 2/2 net-next] net: move qdisc ingress filtering code
 where it belongs

On Mon, 2015-05-11 at 16:02 -0700, Alexei Starovoitov wrote:
> On 5/11/15 7:35 AM, Eric Dumazet wrote:
> >
> > -static inline int deliver_skb(struct sk_buff *skb,
> > +static noinline int deliver_skb(struct sk_buff *skb,
> >   			      struct packet_type *pt_prev,
> >   			      struct net_device *orig_dev)
> 
> have tried the above only and didn't see any difference
> for simple 'netif_receive + drop in ip_rcv' test.
> Not sure whether it's actually worth doing. I would leave it as-is.

Yes, this was probably too aggressive.

unlikely() or static_key_false() are no moving code away enough, whole
function including unused code pollutes icache.

Code size increased a lot, while L1/L2 caches on cpu are about the same
than 6 years ago.

For example , commit 7866a621043fbaca3d7389e9b9f69dd1a2e5a855
helped a given workload, but probably made things slower for most common
cases.



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