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SubjectRe: [PATCH] net: mv643xx_eth: Add GRO support
From
On Thu, Apr 11, 2013 at 3:13 PM, Willy Tarreau <w@1wt.eu> wrote:
> On Thu, Apr 11, 2013 at 02:40:23PM +0200, Sebastian Hesselbarth wrote:
>> This patch adds GRO support to mv643xx_eth by making it invoke
>> napi_gro_receive instead of netif_receive_skb.
>>
>> Signed-off-by: Soeren Moch <smoch@web.de>
>> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
>> ---
>> Cc: "David S. Miller" <davem@davemloft.net>
>> Cc: Lennert Buytenhek <buytenh@wantstofly.org>
>> Cc: Andrew Lunn <andrew@lunn.ch>
>> Cc: Jason Cooper <jason@lakedaemon.net>
>> Cc: Florian Fainelli <florian@openwrt.org>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Dale Farnsworth <dale@farnsworth.org>
>> Cc: netdev@vger.kernel.org
>> Cc: linux-arm-kernel@lists.infradead.org
>> Cc: linuxppc-dev@lists.ozlabs.org
>> Cc: linux-kernel@vger.kernel.org
>> ---
>> drivers/net/ethernet/marvell/mv643xx_eth.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/marvell/mv643xx_eth.c b/drivers/net/ethernet/marvell/mv643xx_eth.c
>> index 305038f..c850d04 100644
>> --- a/drivers/net/ethernet/marvell/mv643xx_eth.c
>> +++ b/drivers/net/ethernet/marvell/mv643xx_eth.c
>> @@ -604,7 +604,7 @@ static int rxq_process(struct rx_queue *rxq, int budget)
>> lro_receive_skb(&rxq->lro_mgr, skb, (void *)cmd_sts);
>> lro_flush_needed = 1;
>> } else
>> - netif_receive_skb(skb);
>> + napi_gro_receive(&mp->napi, skb);
>>
>> continue;
>
> I remember having experimented with this on 3.6 a few months ago with this
> driver and finally switching back to something like this instead which
> showed better performance on my tests :
>
> if (skb->ip_summed == CHECKSUM_UNNECESSARY)
> napi_gro_receive(napi, skb);
> else
> netif_receive_skb(skb);
>
> Unfortunately I don't have more details as my commit message was rather
> short due to this resulting from experimentation. Did you verify that
> you did not lose any performance in various workloads ? I was playing
> with bridges at this time, it's possible that I got better performance
> on bridging with netif_receive_skb() than with napi_gro_receive().

Hi Willy,

I did some simple tests on Dove/Cubox with 'netperf -cCD' and
gso/gro/lro options on
mv643xx_eth. The tests may not be sufficient, as I am not that into
net performance
testing.

I tried todays net-next on top of 3.9-rc6 without any gro patch, with
the initial
patch (Soeren) and your proposed patch (Willy). The results show that
both patches
allow a significant increase in throughput compared to
netif_receive_skb (!gro, !lro)
alone. Having gro with lro disabled gives some 2% more throughput
compared to lro only.

Sebastian

Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB

87380 16384 16384 10.02 615.65 19.15 99.90 5.097
13.293 (3.9-rc6: gso)
87380 16384 16384 10.02 615.82 19.05 99.90 5.067
13.289 (3.9-rc6: gso, gro)
87380 16384 16384 10.03 747.44 23.17 99.80 5.079
10.938 (3.9-rc6: gso, lro)
87380 16384 16384 10.02 745.28 22.57 99.80 4.963
10.970 (3.9.rc6: gso, gro, lro)

87380 16384 16384 10.02 600.34 19.10 99.90 5.211
13.632 (3.9-rc6+soeren: gso)
87380 16384 16384 10.02 764.23 23.42 99.80 5.021
10.698 (3.9-rc6+soeren: gso, gro)
87380 16384 16384 10.02 749.81 23.13 99.80 5.055
10.904 (3.9-rc6+soeren: gso, lro)
87380 16384 16384 10.02 745.84 22.34 99.80 4.907
10.962 (3.9.rc6+soeren: gso, gro, lro)

87380 16384 16384 10.02 605.79 18.79 100.00 5.082
13.523 (3.9-rc6+willy: gso)
87380 16384 16384 10.02 765.64 24.68 99.80 5.281
10.678 (3.9-rc6+willy: gso, gro)
87380 16384 16384 10.02 750.30 26.02 99.80 5.682
10.897 (3.9-rc6+willy: gso, lro)
87380 16384 16384 10.03 749.40 21.86 99.80 4.778
10.910 (3.9.rc6+willy: gso, gro, lro)


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