netdev - Re: [PATCH net-next] net: gro: add a per device gro flush timer

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Date:	Wed, 05 Nov 2014 18:14:15 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Rick Jones <rick.jones2@...com>
Cc:	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Or Gerlitz <ogerlitz@...lanox.com>,
	Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next] net: gro: add a per device gro flush timer

On Wed, 2014-11-05 at 17:38 -0800, Rick Jones wrote:

> Speaking of QPS, what happens to 200 TCP_RR tests when the feature is 
> enabled?

Nothing at all (but the usual noise I guess)

200 TCP_RR send packets with 1 byte of payload and Push flag,
so no packet ever sits in napi->gro_list

lpaa5:~# echo 0 >/sys/class/net/eth0/gro_flush_timeout
lpaa6:~# echo 0 >/sys/class/net/eth0/gro_flush_timeout
lpaa5:~# time ./super_netperf 200 -H lpaa6 -t TCP_RR -l 20
3.13827e+06

real	0m32.170s
user	0m32.885s
sys	7m38.868s

lpaa5:~# echo 2000 >/sys/class/net/eth0/gro_flush_timeout
lpaa6:~# echo 2000 >/sys/class/net/eth0/gro_flush_timeout
lpaa5:~# time ./super_netperf 200 -H lpaa6 -t TCP_RR -l 20
3.19013e+06

real	0m37.152s
user	0m33.477s
sys	7m30.586s

Now lets try TCP_RR with -- -r 4000,4000 ;)

Reducing ACK packets allow us to better use the 10Gbe bandwith for
payload, so QPS actually increase.

lpaa5:~# echo 0 >/sys/class/net/eth0/gro_flush_timeout
lpaa6:~# echo 0 >/sys/class/net/eth0/gro_flush_timeout
lpaa5:~# time ./super_netperf 200 -H lpaa6 -t TCP_RR -l 20 -- -r
4000,4000
379645

real	0m32.201s
user	0m4.390s
sys	0m59.501s

lpaa5:~# echo 2000 >/sys/class/net/eth0/gro_flush_timeout
lpaa6:~# echo 2000 >/sys/class/net/eth0/gro_flush_timeout
lpaa5:~# time ./super_netperf 200 -H lpaa6 -t TCP_RR -l 20 -- -r
4000,4000
400610

real	0m37.159s
user	0m4.501s
sys	0m59.665s




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