Re: [Qemu-devel] Partial NUMA config

[Alexey Kardashevskiy]

On 13/3/18 1:26 pm, Alexey Kardashevskiy wrote:
> Hi Igor,
> 
> ec78f8114bc4c1 "numa: use possible_cpus for not mapped CPUs check" added a
> warning about "All CPU(s) up to maxcpus should be described in NUMA config,
> ability to start up with partial NUMA mappings is obsoleted and will be
> removed in future" and this is printed when I add a numa node without
> attached CPU like this:
> 
> -numa node,nodeid=0,cpus=0,mem=4G
> -numa node,nodeid=1,mem=131072M
> 
> And the reason for this command line is that I am trying to pass some dodgy
> host RAM (actually belongs to a GPU but directly accessible via a fast
> NVLink, not PCI fabric) which let's say is equally far from all CPUs, at
> least in the host's NUMA config this memory is also not bound to any CPU:
> 
> address@hidden ~]$ ssh yc02goos numactl -H
> available: 8 nodes (0,8,250-255)
> node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
> 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
> 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
> node 0 size: 261735 MB
> node 0 free: 258932 MB
> node 8 cpus: 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84
> 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106
> 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125
> 126 127
> node 8 size: 261739 MB
> node 8 free: 261414 MB
> node 250 cpus:
> node 250 size: 15360 MB
> node 250 free: 15359 MB
> node 251 cpus:
> node 251 size: 0 MB
> node 251 free: 0 MB
> node 252 cpus:
> node 252 size: 15360 MB
> node 252 free: 15359 MB
> node 253 cpus:
> node 253 size: 15360 MB
> node 253 free: 15359 MB
> node 254 cpus:
> node 254 size: 15360 MB
> node 254 free: 15359 MB
> node 255 cpus:
> node 255 size: 15360 MB
> node 255 free: 15359 MB
> node distances:
> node   0   8  250  251  252  253  254  255
>   0:  10  40  80  80  80  80  80  80
>   8:  40  10  80  80  80  80  80  80
>  250:  80  80  10  80  80  80  80  80
>  251:  80  80  80  10  80  80  80  80
>  252:  80  80  80  80  10  80  80  80
>  253:  80  80  80  80  80  10  80  80
>  254:  80  80  80  80  80  80  10  80
>  255:  80  80  80  80  80  80  80  10
> 
> 
> I am not sure I'll progress far enough to get this working with VFIO but if
> I do, I'd like to keep an ability to have such a partial config in the
> future. What was the reason for this warning in the first place?

Ping?



-- 
Alexey