What are the available features of this emulation tool and how do I set it up (MEMU Version)?

[aaqdas]

Hi,

I understand that the tool has the following features (MEMU Version)

• Simulates Multiple Hosts
• Multiple Hosts can Share a CXL 3.0 Memory Device
• Supports Back-Invalidate Snoops

Here is how we build the tool and simulate

• Build the QEMU Integration

cd qemu_integration && mkdir build
cd build 
cmake ...
make -j 8
sudo make install

• Start MemSim Server and QEMU VMs (after adjusting the hostnames and IPs in CXL Images)

# Inside qemu_integration/build
./start_server 9999 ./topology_simple.txt
# In Terminal 1
../launch_qemu_cxl.sh
# In Terminal 2
../launch_qemu_cxl1.sh

• Expose CXL Memory Node as a DAX

# In both QEMU VMs, run the following
sh ./setup_cxl_numa.sh # Make sure to adjust the IP 

I want to make sure the steps I have performed are in line with the setup. I want to simulate two hosts which share a Type 3 CXL memory device and see the requests on back-invalidate snoop channel

How do I run a workload on both QEMU virtual machines and how utilize the shared memory?

[vickiegpt]

BI is an experimental feature, may need our mutual extra development.

I think the Dax will be exposed as listed in the VM. You can test BI by clflush and sfence.

[aaqdas]

1. Alrighty. Aside from back-invalidation, does this version support multiple hosts connected to the same CXL 3.0 Memory Device? I want the following topology.

        CPU 1
      /
Type 3 CXL
      \
        CPU 2

2. I've setup the virtual machines using the steps I have listed above and launched qemu_integration/build/cxl_memsim_server. However, I do not see any statistics in the server terminal when I run test_cxl_mem in QEMU Virtual Machines. How do I approach that?

[vickiegpt]

1. Alrighty. Aside from back-invalidation, does this version support multiple hosts connected to the same CXL 3.0 Memory Device? I want the following topology.

        CPU 1
      /
Type 3 CXL
      \
        CPU 2

2. I've setup the virtual machines using the steps I have listed above and launched qemu_integration/build/cxl_memsim_server. However, I do not see any statistics in the server terminal when I run test_cxl_mem in QEMU Virtual Machines. How do I approach that?

1. You definitely can do that with topology configured.

2. You can printout the stats periodically on the server side.

Maybe we can schedule zoom meetings some time?

[aaqdas]

Yes, we can schedule a zoom meeting. I can reach out on your email for scheduling a meeting