NUMA CPU affinity issues

[Rama27]

I have a Ubuntu server with 22.04 OS. I encountered an issue with NUMA affinity bound.

1.) Server has two NUMA nodes accordingly.

server-1:# numactl -H
available: 2 nodes (0-1)
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 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143
node 0 size: 1031782 MB
node 0 free: 989481 MB
node 1 cpus: 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 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 95 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191
node 1 size: 1021920 MB
node 1 free: 1018313 MB
node distances:
node   0   1
  0:  10  21
  1:  21  10

2.) When I setting CPU Affinity for a new process with cpu 0 which is part of numa node0, it spanned multiple cpu's among both numa nodes.

server-1:# taskset -c 1 cat /dev/random >& /dev/null &
[1] 691247

server-1:# taskset -cp 691247
pid 691247's current affinity list: 0,1,30,48-51,96,97,144-147

I think it should stick to cpu 1 only rather than multi cpu. Not sure why taskset always shows "current affinity list: 0,1,30,48-51,96,97,144-147" though we changed coreCan you please let me know how this happened.

[Sachinks]

Hello Rama27,

Thank you for your reply.

We have checked this with our internal team these are the suggestions given by them.

NUMA (Non-uniform Memory Access) features are managed by board's Basic Input/Output System - BIOS. The CPU will only provide the architecture to this feature be enabled, which is present on Intel Xeon 8260.

The guides orient to "Explicitly set CPU affinity for affected processes using tools like 'taskset' or 'numactl' to ensure they remain on specific CPUs or NUMA nodes", however this needs to be done explicitly on the BIOS or OS level.

Unfortunately, as we do not provide OS configurations and as the BIOS is from Lenovo, we request you to review this with the board manufacturer.

Also as per the article : https://www.intel.com/content/www/us/en/support/articles/000055440/processors/intel-xeon-processors.html for Intel® Xeon® 8260 (2nd Gen Intel® Xeon® Processors) the OS support is for Ubuntu 16.04/18.04. We have not tested and validated other distributions for the Intel® Xeon® 8260.

You can also refer the below article to know about NUMA and Intel Xeon processors.

Link : https://www.intel.com/content/dam/www/public/us/en/documents/articles/parallel-universe-issue-37.pdf

Hence, we request you to check the NUMA config directly with the OS provider and the BIOS vendor.

Thank you for understanding.

Regards,

Sachin KS

[Sachinks]

Hello Rama27,

Greetings for the day!

I hope this message finds you well.

We are following up to find out if you were able to find the information we provided. 

Kindly reply back to confirm and let us know if have any other queries.

Thank you for using Intel products and services.

Regards,

Sachin KS

[Sachinks]

Hello Rama27,

Greetings for the day!

I hope this message finds you well.

We would like to inform you that we are closing this request as no response has been received from our previous follow-ups. 

Please don't hesitate to ask any further questions in the future. Feel free to start a new conversation, as this thread will no longer be monitored.

Regards,

Sachin KS