eecheng87 / mflexsc

To rewrok FlexSC in linux kernel

mFlexSC

This project try to rework experiment done in paper: FlexSC. There're two main strategies and implemented in this project: batching system call and M-N threading.

Build

build kernel module mFlexsc

cd module
sudo make
make ins

use testing program

cd user
make
./app

If FlexSC applied, need to config(define) FLEXSC in app.c. Otherwise, normal system call doesn't need to config anything.

Overview

Each kernel visible thread bound in specific CPU, in this project, bound in CPU1 and CPU2. There're several user level threads belong to those CPU and storing information(system call number and its arguments) about request into syscall page. Syscall page is shared memory between kernel space and user space, both can access the information on it. Also, each kernel visible thread has their own syscall page. In kernel space, there is a scanner thread ceaselessly searching available entry. If found available(submitted) status, kernel work thread(actually I use linux workqueue) start calling system call requested in user space. As same as user space did, I bound groups of kernel threads in CPU3 and CPU4.

Experiment

There're some experiments I made under /experiment and it seems that FlexSC get better porformance than normal system call.

Reference

spinlock/flexsc

rupc/flexsc

foxhoundsk/FlexSC

mflexsc's Issues

Incomplete system call de-coupling

It is not complete enough to decouple system call into user space and kernel space in current work. The only thing I did is
storing system call number and its arguments. It seems that more information need to provide when using system call table
in kernel space.

For example, call getpid() who didn't need arguments will fail. It will return kernel thread's PID instead of the PID of user program requested in user space.