BWLOCK: memory bandwidth control API

Heechul Yun heechul.yun@ku.edu

In multicore platforms, memory intensive code sections of a program can be significantly delayed by other memory intensive programs running in parallel due to memory bandwidth contention. BWLOCK provides explicit ways to mitigate memory bandwidth contention to protect performance of real-time applications without any special hardware support.

Preparation

Patch the kernel (v3.6) as follows.

   $ patch -p1 < bwlock-3.6.patch 

Configure the kernel to enable BWLOCK.

   CONFIG_BWLOCK=y

Install & boot the BWLOCK enabled kernel.

Build & install the bwlock kernel module

   $ make 
   $ sudo insmod bwlockmod.ko 

Usage

coarse grain locking

If you do the following, the process will be bw locked whenever it is scheduled by the scheduler.

  ./bwlockset <pid> <bwlock_value>

Example)
  $ ./bwlockset `pidof X` 1
  set pid=2559 val=1

fine-grain locking

To support fine-grain bw locking, you need to modify the program to use bw_lock()/bw_unlock().

  #include "bwlock.h"
  
  bw_lock()
  ...
  bw_unlock()

Publication

Heechul Yun, Santosh Gondi, Siddhartha Biswas. "Protecting Memory-Performance Critical Sections in Soft Real-Time Applications," In submission. (pdf)