netdev - Re: [PATCH nf-next,RFC 0/5] Netfilter egress hook

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Date:   Sat, 23 Nov 2019 14:11:08 +0100
From:   Lukas Wunner <lukas@...ner.de>
To:     Pablo Neira Ayuso <pablo@...filter.org>
Cc:     Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org, Martin Mares <mj@....cz>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [PATCH nf-next,RFC 0/5] Netfilter egress hook

On Thu, Nov 07, 2019 at 11:51:49PM +0100, Pablo Neira Ayuso wrote:
> On Thu, Oct 31, 2019 at 02:41:00PM +0100, Lukas Wunner wrote:
> > Introduce a netfilter egress hook to complement the existing ingress hook.
> 
> Would you provide some numbers on the performance impact for this new
> hook?

For some reason the numbers are slightly better with this series.

Could be caused by the __always_inline in patch 4, I'd have to compare
the disassembly to confirm this hunch.


* Without this patch:
  Result: OK: 34205373(c34202809+d2564) usec, 100000000 (60byte,0frags)
  2923517pps 1403Mb/sec (1403288160bps) errors: 0

* With this patch:
  Result: OK: 34106013(c34103172+d2841) usec, 100000000 (60byte,0frags)
  2932034pps 1407Mb/sec (1407376320bps) errors: 0


* Without this patch + tc egress:
  Result: OK: 37848652(c37846140+d2511) usec, 100000000 (60byte,0frags)
  2642102pps 1268Mb/sec (1268208960bps) errors: 0

* With this patch + tc egress:
  Result: OK: 37784817(c37782026+d2791) usec, 100000000 (60byte,0frags)
  2646565pps 1270Mb/sec (1270351200bps) errors: 0


* With this patch + nft egress:
  Result: OK: 43911936(c43908932+d3003) usec, 100000000 (60byte,0frags)
  2277285pps 1093Mb/sec (1093096800bps) errors: 0


Tested on a bare-metal Core i7-3615QM, each measurement was performed
twice to verify that the numbers are stable.

Commands to perform a measurement:
modprobe pktgen
echo "add_device lo@3" > /proc/net/pktgen/kpktgend_3
samples/pktgen/pktgen_bench_xmit_mode_queue_xmit.sh -i 'lo@3' -n 100000000

Commands for testing tc egress:
tc qdisc add dev lo clsact
tc filter add dev lo egress protocol ip prio 1 u32 match ip dst 4.3.2.1/32

Commands for testing nft egress:
nft add table netdev t
nft add chain netdev t co \{ type filter hook egress device lo priority 0 \; \}
nft add rule netdev t co ip daddr 4.3.2.1/32 drop

All testing was performed on the loopback interface to avoid distorting
measurements by the packet handling in the low-level Ethernet driver.
This required the following small patch:


diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index bb99152..020c825 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2003,8 +2003,8 @@ static int pktgen_setup_dev(const struct pktgen_net *pn,
 		return -ENODEV;
 	}
 
-	if (odev->type != ARPHRD_ETHER) {
-		pr_err("not an ethernet device: \"%s\"\n", ifname);
+	if (odev->type != ARPHRD_ETHER && odev->type != ARPHRD_LOOPBACK) {
+		pr_err("not an ethernet or loopback device: \"%s\"\n", ifname);
 		err = -EINVAL;
 	} else if (!netif_running(odev)) {
 		pr_err("device is down: \"%s\"\n", ifname);