18.1. Introduction

this part has been written by Amit Shah

There's not much documentation available right now for the kernel. I hope to write some in the coming weeks. Anyways, here's how the sources are laid out:

The openMosix code resides largely in hpc/ and include/hpc. There are lots of patches to the core kernel files everywhere, right from the arch/i386 directories to mm/, fs/, etc. You need to read up the code which interests you and think that would matter for the present situation (that shouldn't be a problem, since you've done kernel coding).

here's what you should expect in each of the source files:

• hpc/badops.c: one file to handle all the bad operations: mostly return err codes

• hpc/balance.c: The load balancer code (load + mem usage + n/w usage)

• hpc/comm.c: The intra-cluster communication setup

• hpc/config.c: The config code for openMosix: after you run the startup script

• hpc/decay.c: decay (age) the stats and info collected from other nodes

• hpc/deputy.c: Code executed on the deputy: service remote syscalls (ie. after the process has migrated), signals, etc.

• hpc/dfsa.c: Direct File System Access code: the distributed file system abstraction layer

• hpc/div.c: the algorithms to do floating point divisions

• hpc/export.c: export symbols needed in other files

• hpc/freemem.c: to keep track of free, avl. memory and to free it if need be. hugely taken from the Linux mm/ code.

• hpc/hpcadmin.c: tune openMosix admin values (through /proc/hpc)

• hpc/hpcproc.c: The /proc/hpc code is handled here

• hpc/info.c: The info daemon: sends and receives (multicast) load+mem usage stats throughout the cluster

• hpc/init.c: Initialization code: initializes the daemons, etc.

• hpc/kernel.c: most of the "core" code: all the important algorithms, decisions, etc. made here.

• hpc/load.c: calculation of local load, etc.

• hpc/mig.c: Code that handles the migration. Code in this file is invoked on any migration: deputy->remote, remote->deputy; remote->remote

• hpc/prequest.c: handles the process's requests: signals, more memory, etc.

• hpc/remote.c: Code executed when the process is on the remote: syscalls handling on remote, passing control to deputy, etc.

• hpc/rinode.c: fs/ related stuff: used mostly for DFSA

• hpc/service.c: setting up daemons, getting memory, etc.

• hpc/syscalls.c: handles all the remote syscalls here

• hpc/ucache.c: handles the ucache: mostly mm/, fs/ stuff.

the other files like auto_syscalls.c, alternate.c are generated at compile time.