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I just upgraded a DL585 g7 server by replacing its Opteron 6172 CPUs with 4 Opteron 6274 CPUs. Every source I read says that the Opteron 6274s are supposed to have 8x2MB of L2 Cache and 16MB of L3 cache, but Windows Server 2016 says that all four processors together have only 48MB of L3 cache (i.e. 12MB ea.), though the expected 64MB of L2 cache. These are production chips, not engineering samples, as confirmed in CPU-z and by reading the text on them.

When the server boots, however, the BIOS readout identifies each CPU as having 16MB L2 and 16MB L3, unlike Windows Server 2016 and CPU-z running in Windows Server.

Do you think the manufacturer just wrote the wrong number in their documentation? I know that lower steppings of the 6200 Opteron series have only 2x6MB of L3 cache. But I looked to see if anyone else had this problem and found nothing. Or did I happen to get 4 chips that all have bad L3 cache? Or could some motherboard setting be preventing my operating system from seeing all the cache?

Thank you for your time.

C.P.
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HT assist is turned on in the bios. it uses cache to help speed up access.On my system it uses 4MB per cpu (16MB - 4MB = 12MB). 12MBx4 = 48MB.

Turn HT assist off in the bios, and you will see more L3 cache, but multi processor performance will go down.

http://www.qdpma.com/systemarchitecture/SystemArchitecture_Opteron.html

Sheldon Irving
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