Re: [Qemu-devel] [PATCH 00/12] Multiqueue virtio-net

[Jason Wang]

On 01/10/2013 07:49 PM, Stefan Hajnoczi wrote:
> On Thu, Jan 10, 2013 at 05:34:14PM +0800, Jason Wang wrote:
>> On 01/10/2013 04:44 PM, Stefan Hajnoczi wrote:
>>> On Wed, Jan 09, 2013 at 11:33:25PM +0800, Jason Wang wrote:
>>>> On 01/09/2013 11:32 PM, Michael S. Tsirkin wrote:
>>>>> On Wed, Jan 09, 2013 at 03:29:24PM +0100, Stefan Hajnoczi wrote:
>>>>>> On Fri, Dec 28, 2012 at 06:31:52PM +0800, Jason Wang wrote:
>>>>>>> Perf Numbers:
>>>>>>>
>>>>>>> Two Intel Xeon 5620 with direct connected intel 82599EB
>>>>>>> Host/Guest kernel: David net tree
>>>>>>> vhost enabled
>>>>>>>
>>>>>>> - lots of improvents of both latency and cpu utilization in 
>>>>>>> request-reponse test
>>>>>>> - get regression of guest sending small packets which because TCP tends 
>>>>>>> to batch
>>>>>>>   less when the latency were improved
>>>>>>>
>>>>>>> 1q/2q/4q
>>>>>>> TCP_RR
>>>>>>>  size #sessions trans.rate  norm trans.rate  norm trans.rate  norm
>>>>>>> 1 1     9393.26   595.64  9408.18   597.34  9375.19   584.12
>>>>>>> 1 20    72162.1   2214.24 129880.22 2456.13 196949.81 2298.13
>>>>>>> 1 50    107513.38 2653.99 139721.93 2490.58 259713.82 2873.57
>>>>>>> 1 100   126734.63 2676.54 145553.5  2406.63 265252.68 2943
>>>>>>> 64 1    9453.42   632.33  9371.37   616.13  9338.19   615.97
>>>>>>> 64 20   70620.03  2093.68 125155.75 2409.15 191239.91 2253.32
>>>>>>> 64 50   106966    2448.29 146518.67 2514.47 242134.07 2720.91
>>>>>>> 64 100  117046.35 2394.56 190153.09 2696.82 238881.29 2704.41
>>>>>>> 256 1   8733.29   736.36  8701.07   680.83  8608.92   530.1
>>>>>>> 256 20  69279.89  2274.45 115103.07 2299.76 144555.16 1963.53
>>>>>>> 256 50  97676.02  2296.09 150719.57 2522.92 254510.5  3028.44
>>>>>>> 256 100 150221.55 2949.56 197569.3  2790.92 300695.78 3494.83
>>>>>>> TCP_CRR
>>>>>>>  size #sessions trans.rate  norm trans.rate  norm trans.rate  norm
>>>>>>> 1 1     2848.37  163.41 2230.39  130.89 2013.09  120.47
>>>>>>> 1 20    23434.5  562.11 31057.43 531.07 49488.28 564.41
>>>>>>> 1 50    28514.88 582.17 40494.23 605.92 60113.35 654.97
>>>>>>> 1 100   28827.22 584.73 48813.25 661.6  61783.62 676.56
>>>>>>> 64 1    2780.08  159.4  2201.07  127.96 2006.8   117.63
>>>>>>> 64 20   23318.51 564.47 30982.44 530.24 49734.95 566.13
>>>>>>> 64 50   28585.72 582.54 40576.7  610.08 60167.89 656.56
>>>>>>> 64 100  28747.37 584.17 49081.87 667.87 60612.94 662
>>>>>>> 256 1   2772.08  160.51 2231.84  131.05 2003.62  113.45
>>>>>>> 256 20  23086.35 559.8  30929.09 528.16 48454.9  555.22
>>>>>>> 256 50  28354.7  579.85 40578.31 607    60261.71 657.87
>>>>>>> 256 100 28844.55 585.67 48541.86 659.08 61941.07 676.72
>>>>>>> TCP_STREAM guest receiving
>>>>>>>  size #sessions throughput  norm throughput  norm throughput  norm
>>>>>>> 1 1     16.27   1.33   16.1    1.12   16.13   0.99
>>>>>>> 1 2     33.04   2.08   32.96   2.19   32.75   1.98
>>>>>>> 1 4     66.62   6.83   68.3    5.56   66.14   2.65
>>>>>>> 64 1    896.55  56.67  914.02  58.14  898.9   61.56
>>>>>>> 64 2    1830.46 91.02  1812.02 64.59  1835.57 66.26
>>>>>>> 64 4    3626.61 142.55 3636.25 100.64 3607.46 75.03
>>>>>>> 256 1   2619.49 131.23 2543.19 129.03 2618.69 132.39
>>>>>>> 256 2   5136.58 203.02 5163.31 141.11 5236.51 149.4
>>>>>>> 256 4   7063.99 242.83 9365.4  208.49 9421.03 159.94
>>>>>>> 512 1   3592.43 165.24 3603.12 167.19 3552.5  169.57
>>>>>>> 512 2   7042.62 246.59 7068.46 180.87 7258.52 186.3
>>>>>>> 512 4   6996.08 241.49 9298.34 206.12 9418.52 159.33
>>>>>>> 1024 1  4339.54 192.95 4370.2  191.92 4211.72 192.49
>>>>>>> 1024 2  7439.45 254.77 9403.99 215.24 9120.82 222.67
>>>>>>> 1024 4  7953.86 272.11 9403.87 208.23 9366.98 159.49
>>>>>>> 4096 1  7696.28 272.04 7611.41 270.38 7778.71 267.76
>>>>>>> 4096 2  7530.35 261.1  8905.43 246.27 8990.18 267.57
>>>>>>> 4096 4  7121.6  247.02 9411.75 206.71 9654.96 184.67
>>>>>>> 16384 1 7795.73 268.54 7780.94 267.2  7634.26 260.73
>>>>>>> 16384 2 7436.57 255.81 9381.86 220.85 9392    220.36
>>>>>>> 16384 4 7199.07 247.81 9420.96 205.87 9373.69 159.57
>>>>>>> TCP_MAERTS guest sending
>>>>>>>  size #sessions throughput  norm throughput  norm throughput  norm
>>>>>>> 1 1     15.94   0.62   15.55   0.61   15.13   0.59
>>>>>>> 1 2     36.11   0.83   32.46   0.69   32.28   0.69
>>>>>>> 1 4     71.59   1      68.91   0.94   61.52   0.77
>>>>>>> 64 1    630.71  22.52  622.11  22.35  605.09  21.84
>>>>>>> 64 2    1442.36 30.57  1292.15 25.82  1282.67 25.55
>>>>>>> 64 4    3186.79 42.59  2844.96 36.03  2529.69 30.06
>>>>>>> 256 1   1760.96 58.07  1738.44 57.43  1695.99 56.19
>>>>>>> 256 2   4834.23 95.19  3524.85 64.21  3511.94 64.45
>>>>>>> 256 4   9324.63 145.74 8956.49 116.39 6720.17 73.86
>>>>>>> 512 1   2678.03 84.1   2630.68 82.93  2636.54 82.57
>>>>>>> 512 2   9368.17 195.61 9408.82 204.53 5316.3  92.99
>>>>>>> 512 4   9186.34 209.68 9358.72 183.82 9489.29 160.42
>>>>>>> 1024 1  3620.71 109.88 3625.54 109.83 3606.61 112.35
>>>>>>> 1024 2  9429    258.32 7082.79 120.55 7403.53 134.78
>>>>>>> 1024 4  9430.66 290.44 9499.29 232.31 9414.6  190.92
>>>>>>> 4096 1  9339.28 296.48 9374.23 372.88 9348.76 298.49
>>>>>>> 4096 2  9410.53 378.69 9412.61 286.18 9409.75 278.31
>>>>>>> 4096 4  9487.35 374.1  9556.91 288.81 9441.94 221.64
>>>>>>> 16384 1 9380.43 403.8  9379.78 399.13 9382.42 393.55
>>>>>>> 16384 2 9367.69 406.93 9415.04 312.68 9409.29 300.9
>>>>>>> 16384 4 9391.96 405.17 9695.12 310.54 9423.76 223.47
>>>>>> Trying to understand the performance results:
>>>>>>
>>>>>> What is the host device configuration?  tap + bridge?
>>>> Yes.
>>>>>> Did you use host CPU affinity for the vhost threads?
>>>> I use numactl to pin cpu threads and vhost threads in the same numa node.
>>>>>> Can multiqueue tap take advantage of multiqueue host NICs or is
>>>>>> virtio-net multiqueue unaware of the physical NIC multiqueue
>>>>>> capabilities?
>>>> Tap is unware of the physical multiqueue NIC, but we can benefit from it
>>>> since we use multiple vhost threads.
>>> I wonder if it makes a difference to bind tap queues to physical NIC
>>> queues.  Maybe this is only possible in macvlan or can you preset the
>>> queue index of outgoing skbs so the network stack doesn't recalculate
>>> the flow?
>> There are some issues here:
>>
>> - For tap, we know nothing about the physical card, especially how many
>> queues it has.
>> - We can present the queue index information in the skb. But there's not
>> a standard txq selection / rxq smp affinity setting method for
>> multiqueue card driver in linux. For example, ixgbe and efx use
>> completely different method. So we can easily find a method for ixgbe
>> but not all others.
> It's an interesting problem because it seems like doing multiqueue
> through the entire stack would be more efficient than doing multiqueue
> twice at different layers.

Yes, I admit that more co-operation on the whole stack is better. Anyway
we can start from this series and improve on top.
> I wonder how much of a difference it can make.

Not an easy task at least form the point of my view. May need 1) unify
the flow steering mechanism of all mq drivers or cards 2) passing more
information between various layers.
> Stefan