netdev - Re: [EXT] Re: [PATCH net-next 3/5] net: mvpp2: cls: Use RSS contexts to handle RSS tables

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Date:   Wed, 20 May 2020 12:10:43 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Matteo Croce <mcroce@...hat.com>
Cc:     Antoine Tenart <antoine.tenart@...tlin.com>,
        netdev <netdev@...r.kernel.org>,
        "gregory.clement@...tlin.com" <gregory.clement@...tlin.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>,
        Nadav Haklai <nadavh@...vell.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.com>,
        Stefan Chulski <stefanc@...vell.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        "David S . Miller" <davem@...emloft.net>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [EXT] Re: [PATCH net-next 3/5] net: mvpp2: cls: Use RSS contexts
 to handle RSS tables

On Tue, May 19, 2020 at 07:05:34PM +0200, Matteo Croce wrote:
> On Tue, 19 May 2020 12:05:20 +0200
> Matteo Croce <mcroce@...hat.com> wrote:
> 
> Hi,
> 
> The patch seems to work. I'm generating traffic with random MAC and IP
> addresses, to have many flows:
> 
> # tcpdump -tenni eth2
> 9a:a9:b1:3a:b1:6b > 00:51:82:11:22:02, ethertype IPv4 (0x0800), length 60: 10.0.0.4.0 > 192.168.0.4.0: UDP, length 12
> 9e:92:fd:f8:7f:0a > 00:51:82:11:22:02, ethertype IPv4 (0x0800), length 60: 10.0.0.4.0 > 192.168.0.4.0: UDP, length 12
> 66:b7:11:8a:c2:1f > 00:51:82:11:22:02, ethertype IPv4 (0x0800), length 60: 10.0.0.1.0 > 192.168.0.1.0: UDP, length 12
> 7a:ba:58:bd:9a:62 > 00:51:82:11:22:02, ethertype IPv4 (0x0800), length 60: 10.0.0.1.0 > 192.168.0.1.0: UDP, length 12
> 7e:78:a9:97:70:3a > 00:51:82:11:22:02, ethertype IPv4 (0x0800), length 60: 10.0.0.2.0 > 192.168.0.2.0: UDP, length 12
> b2:81:91:34:ce:42 > 00:51:82:11:22:02, ethertype IPv4 (0x0800), length 60: 10.0.0.2.0 > 192.168.0.2.0: UDP, length 12
> 2a:05:52:d0:d9:3f > 00:51:82:11:22:02, ethertype IPv4 (0x0800), length 60: 10.0.0.3.0 > 192.168.0.3.0: UDP, length 12
> ee:ee:47:35:fa:81 > 00:51:82:11:22:02, ethertype IPv4 (0x0800), length 60: 10.0.0.3.0 > 192.168.0.3.0: UDP, length 12
> 
> This is the default rate, with rxhash off:
> 
> # utraf eth2
> tx: 0 bps 0 pps rx: 397.4 Mbps 827.9 Kpps
> tx: 0 bps 0 pps rx: 396.3 Mbps 825.7 Kpps
> tx: 0 bps 0 pps rx: 396.6 Mbps 826.3 Kpps
> tx: 0 bps 0 pps rx: 396.5 Mbps 826.1 Kpps
> 
>     PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
>       9 root      20   0       0      0      0 R  99.7   0.0   7:02.58 ksoftirqd/0
>      15 root      20   0       0      0      0 S   0.0   0.0   0:00.00 ksoftirqd/1
>      20 root      20   0       0      0      0 S   0.0   0.0   2:01.48 ksoftirqd/2
>      25 root      20   0       0      0      0 S   0.0   0.0   0:32.86 ksoftirqd/3
> 
> and this with rx hashing enabled:
> 
> # ethtool -K eth2 rxhash on
> # utraf eth2
> tx: 0 bps 0 pps rx: 456.4 Mbps 950.8 Kpps
> tx: 0 bps 0 pps rx: 458.4 Mbps 955.0 Kpps
> tx: 0 bps 0 pps rx: 457.6 Mbps 953.3 Kpps
> tx: 0 bps 0 pps rx: 462.2 Mbps 962.9 Kpps
> 
>     PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
>      20 root      20   0       0      0      0 R   0.7   0.0   2:02.34 ksoftirqd/2
>      25 root      20   0       0      0      0 S   0.3   0.0   0:33.25 ksoftirqd/3
>       9 root      20   0       0      0      0 S   0.0   0.0   7:52.57 ksoftirqd/0
>      15 root      20   0       0      0      0 S   0.0   0.0   0:00.00 ksoftirqd/1
> 
> 
> The throughput doesn't increase so much, maybe we hit an HW limit of
> the gigabit port. The interesting thing is how the global CPU usage
> drops from 25% to 1%.
> I can't explain this, it could be due to the reduced contention?

Hi Matteo,

Can I take that as a Tested-by ?

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC for 0.8m (est. 1762m) line in suburbia: sync at 13.1Mbps down 424kbps up