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TPT

This is the kernel code for "Translation Pass-Through for Near-Native Paging Performance in VMs", Usenix ATC 23. Tested with Ubuntu 20.04.

This source-code is POC and given as-is. Code structure can be improved, otherwise it is entirely functional. Any suggestions are more than welcome!

Components Overview

  • guest_kernel: The TPT guest kernel (with the TPT pv-ops backend).
  • host_kernel: The TPT hypervisor kernel. This is a plain vanilla kernel with a modified KVM module that supports TPT and its emulation on Intel x86_64.
  • qemu: TPT supporting QEMU.
  • run_virt_script: collection of scripts to deploy a TPT/non-TPT VM.

Quick Setup:

Dependencies:

For Linux kernel compilation:

https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel

For QEMU compilation

https://wiki.qemu.org/Hosts/Linux

In each of their respective folders:

Host Kernel

make tpt_defconfig
make -j$(nproc)
sudo make modules_install
sudo make install

Guest Kernel

make tpt_defconfig
make -j$(nproc)

QEMU

mkdir build && cd build
../configure --target-list=x86_64-softmmu  
make -j$(nproc)
sudo make install

Quick Run:

Modify the variables in the script:

run_virt_script/run_virt_general.sh.

And specify the current user and the directory of the kernel and the Ubuntu image.

Run the script to spawn a VM:

./run_virt_general.sh -d

-d flag specifies that the hypervisor exposes TPT

SSH in to the virtual machine.

Run:

echo 1 | sudo tee /sys/kernel/devirt

To fault in all VM pages and map them into EPT to minimize inconsistency between runs.

To spawn a process with TPT, enter its name into /sys/kernel/mm/devirt/task_name

For example:

echo sysbench | sudo tee /sys/kernel/mm/devirt/task_name

Then run the process.

Toy example to show the benefits of TPT with sysbench for random memory accesses:

Spawn a TPT capable VM with ./run_virt_general.sh -d

SSH into the machine:

tpt@tpt:~$ echo 1 | sudo tee /sys/kernel/devirt
1

tpt@tpt:~$ # Run without TPT
tpt@tpt:~$ sysbench memory --memory-block-size=4G --memory-access-mode=rnd run
sysbench 1.0.18 (using system LuaJIT 2.1.0-beta3)
...
General statistics:  
    total time:                          `31.3870s`
    
tpt@tpt:~$ # Enable TPT for Sysbench
tpt@tpt:~$ echo sysbench | sudo tee /sys/kernel/mm/devirt/task_name
tpt@tpt:~$ sysbench memory --memory-block-size=4G --memory-access-mode=rnd run
sysbench 1.0.18 (using system LuaJIT 2.1.0-beta3)
...
General statistics:
   total time:                          `14.9101s`

Results with TPT equal to that of native execution.