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  1. Bug #1391339
  2. Comment #10

Comment 10 for bug 1391339

Revision history for this message
Rodrigo Vaz (rodrigo-vaz) wrote :

Hi Stefan,

Ok I think I've figured out why you were unable to reproduce the slowness, as I mentioned earlier we use the m2 instance type that runs on underlying Xen 3.4 where the t1.micro is probably running on newer infrastructure so I decided to give m3 a try and xen is actually newer (4.2) following is the result of your iperf script on m2 and m3 instances and as you can see the old instance is really affected:

m3 client / m3 server / gro on
Average bandwidth = 958.334 Mbits/sec
StdDev = 21.3581 Mbits/sec

Server Output Sample:
[SUM] 0.0-50.5 sec 5.87 GBytes 1000 Mbits/sec
[ 5] local ... port 5001 connected with ... port 36291
[ 5] 0.0-10.1 sec 1.16 GBytes 984 Mbits/sec
[ 4] local ... port 5001 connected with ... port 36292
[ 4] 0.0-10.1 sec 1.19 GBytes 1.01 Gbits/sec
[ 5] local ... port 5001 connected with ... port 36293
[ 5] 0.0-10.1 sec 1.17 GBytes 997 Mbits/sec
[ 6] local ... port 5001 connected with ... port 36294
[ 6] 0.0-20.2 sec 1.17 GBytes 498 Mbits/sec
[SUM] 0.0-20.2 sec 2.34 GBytes 995 Mbits/sec

m2 client / m3 server / gro on
Average bandwidth = 643.833 Mbits/sec
StdDev = 31.689 Mbits/sec

m2 client / m3 server / gro off
Average bandwidth = 643.744 Mbits/sec
StdDev = 29.4622 Mbits/sec

Server Output Sample:
[ 6] 0.0-181.1 sec 803 MBytes 37.2 Mbits/sec
[ 5] local ... port 5001 connected with ... port 32660
[ 4] 0.0-191.1 sec 802 MBytes 35.2 Mbits/sec
[ 6] local ... port 5001 connected with ... port 32661
[ 5] 0.0-201.2 sec 803 MBytes 33.5 Mbits/sec
[ 4] local ... port 5001 connected with ... port 32662
[ 6] 0.0-211.2 sec 782 MBytes 31.1 Mbits/sec
[ 5] local ... port 5001 connected with ... port 32663
[ 4] 0.0-221.3 sec 798 MBytes 30.2 Mbits/sec
[ 6] local ... port 5001 connected with ... port 32664
[ 5] 0.0-231.4 sec 795 MBytes 28.8 Mbits/sec
[ 4] local ... port 5001 connected with ... port 32665
[ 6] 0.0-241.4 sec 796 MBytes 27.7 Mbits/sec
[ 4] 0.0-251.5 sec 801 MBytes 26.7 Mbits/sec

So looks like the problem happens with Xen prior to 4.2 and I still think it is a regression since the kernel 3.11 handles inbound network traffic better with or without gro.

Thanks,
Rodrigo.