PALLOC is a kernel-level memory allocator that exploits page-based virtual-to-physical memory translation to selectively allocate memory pages of each application to the desired DRAM banks. The goal of PALLOC is to control applications' memory locations in a way to minimize memory performance unpredictability in multicore systems by eliminating bank sharing among applications executing in parallel. PALLOC is a software based solution, which is fully compatible with existing COTS hardware platforms and transparent to applications (i.e., no need to modify application code.)

Note that these instructions apply to new palloc_xormap_ variants. For older palloc patches, see README-old.md.

You can use one of the prepared patches for different Linux kernel versions.

To build the kernel with PALLOC enabled, the following option must be enabled.

CONFIG_CGROUP_PALLOC=y

See drama-pp

For cache partitioning, just use the cache set bits instead of DRAM bank bits.

• Set phsyical address to DRAM bank mapping functions (map.txt output from drama-pp)
  • Direct address maps (e.g., Raspberry Pi 4)

   # cat > map.txt
   12
   13
   14
   # cat map.txt > /sys/kernel/debug/palloc/control
   --> select bit 12, 13, 14. (total banks: 2^3 = 8)
  

  • XOR address maps (e.g., Intel Skylake)

   # cat > map.txt
   14 18
   15 19
   16 20
   17 21
   8 9 12 13 14 15
   # cat map.txt > /sys/kernel/debug/palloc/control
   --> select (14 ^ 18), (15 ^ 19), (16 ^ 20), and (17 ^ 21) and (8 ^ 9 ^ 12 ^ 13 ^ 14 ^ 15) (total bins: 2^5 = 32)
  

• CGROUP partition setting

   # cd /sys/fs/cgroup/palloc
   # mkdir part1
   # cd part1
   # echo 0-3 > palloc.bins
   --> bin 0,1,2,3 are assigned to part1 CGROUP.
   # echo $$ > tasks
   --> when you enable PALLOC, all processes invoked from the shell use pages from the bins 0, 1, 2, or 3.  
  

• Enable PALLOC

   # echo enable > /sys/kernel/debug/palloc/control
   --> enable palloc (owise the default buddy allocator will be used)
  

• Other options

   # echo 1 > /sys/kernel/debug/palloc/debug_level  
   --> enable debug messsages visible through /sys/kernel/debug/tracing/trace.
   # echo 4 > /sys/kernel/debug/palloc/alloc_balance
   --> wait until at least 4 different colors are in the color cache. 
   # echo never > /sys/kernel/mm/transparent_hugepage/enabled
   --> palloc doesn't work with transparent huge page. please disable this.
  

• Heechul Yun, Renato, Zheng-Pei Wu, Rodolfo Pellizzoni. "PALLOC: DRAM Bank-Aware Memory Allocator for Performance Isolation on Multicore Platforms," IEEE Intl. Conference on Real-Time and Embedded Technology and Applications Symposium (RTAS), 2014. (pdf, ppt)