L3 Cache are separated via Intel CAT, but L3 competition exists.

[yanbozyb]

Hello,

I use Intel CAT to separate L3 cache for three VMs (VM1, VM2, VM3). VM1 is allocated with 6 ways (COS 1), VM2 is 4 ways (COS 2), and VM3 is 1 way (CO3). The masks shown via pqos -s are as below. And I allocated cores used by each VM to independent COS.

L3CA COS1 => MASK 0x3f L3CA COS2 => MASK 0x3c0 L3CA COS3 => MASK 0x400

Each VM uses an independent DRAM device, so I expect there is no impact on performance when running Intel MLC concurrently on VMs. However, there is still impact on performance when I run MLC on three VMs concurrently.

I confirmed the allocation above is valid via sudo pqos -s. Is there any clue to figure out what is the root cause of this?

Thanks!

[rkanagar]

Hi @yanbozyb ,
What kind of performance issue is happening?. Please prove logs/screenshots. Thanks