Linux kernel

This extension of linux provides some additional features in linux that facilitates large systems to efficient process in-memory data.

The vmcopy() implementation provides an efficient way to replicate main-memory data. It can replace an expensive malloc() and memcpy() operation to copy data virtually instead of creating physical copy. The copy created by vmcopy() are managed by linux kernel, and is detached from original using copy-on-write (if data is backed by private anonymous memory). The copy retains the properties of original virtual memory area.

Actual linux documentation is available in Documentation/admin-guide/README.rst

Commit hash of first commit 48c0dcc537 (needed to create a patch).

Build requirements for ubuntu 18.04

sudo apt-get install git build-essential kernel-package fakeroot libncurses5-dev libssl-dev ccache bison flex

syscall specification:

SYSCALL_NR 333

void* vmcopy(void* src, unsigned long length);

// use syscall defined in unistd.h to invoke the system call or,
// use the header file (anker.h) defined in rapido/tests/include/

void *copy = syscall(333, src, length);

Configure kernel with VMCOPY support

1. Use make menuconfig to generate a .config file.
2. Enable transparent hugepages by editing .config file.

• Set CONFIG_TRANSPARENT_HUGEPAGE=y and CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y.
• These options are necessary to run the tests specified under rapido/tests/src/

3. Enable vmcopy() by setting CONFIG_ANKER_VMCOPY=y.
4. Currently TRANSPARENT_HUGEPAGE must be enabled to use vmcopy().

Testing the kernel

This kernel was developed using the testbed backed by Qemu. I have used a trimmed down version of Rapido that provides a set of scripts to quicky generate VM Image and necessary modules using Dracut and boots the image using Qemu.

Build instructions

1. Generate relevant configure file as mentioned above.
2. make -j
3. INSTALL_MOD_PATH=./mods make modules_install

Running tests

1. cd rapido/tests
2. cmake -DCMAKE_CXX_FLAGS=-O2 .
3. make -j4
4. cd ..
5. ./cut_anker.sh
6. Boot the VM using ./vm.sh.
7. Tests are installed in path /tests/ inside the VM.
8. Use shutdown to powerdown the VM.

Patching linux

1. Create patch using diff.

• diff -uNr linux.vanilla linux.new > patchfile

2. Apply patch using patch.

• cd linux && patch -p1 < ../patchfile

Mount hugetlbfs

1. echo 2048 > /proc/sys/vm/nr_hugepages
2. mkdir -p /mnt/hugetlbfs
3. chown -R user:group /mnt/hugetlbfs
4. mount -t hugetlbfs -o uid=<userid>,gid=<groupid>,pagesize=2M,size=4G,nr_inodes=1024 none /mnt/hugetlbfs

License

The code and technology is free for academic use. For commercial use, contact [email protected]