|Summary help replacing me|
distcc is a program that distributes source code among a number of distcc-servers. The distcc-daemon sends parts of the source code to the distcc-servers that compile the code and send back the result to the daemon. This way you can use many machines to compile one program and thus speed up the compilation process. The cool part is you can use it together with pacman/srcpac.
- distcc daemon
- The PC or server that's running distcc to distribute the source code. The daemon itself will compile parts of the source code but will also send other parts to the hosts defined in DISTCC_HOSTS.
- distcc server
- The PC or server compiling the source code it gets from the daemon. When it's done compiling, it sends back the object code (i.e. compiled source code) to the daemon, which in turn sends back some more source code (if there's any left to compile).
Install the distcc package from [community] on all PCs in the cluster:
# pacman -S distcc
For other distro's or even OS'es including Windows through using Cygwin, refer to the distcc docs.
Both Daemon and Server(s)
Edit Template:Filename and modify the only uncommented line with the correct IP address or range of your daemon or of your entire subnet:
DISTCC_ARGS="--user nobody --allow 192.168.0.0/24"
Edit Template:Filename and add a line to allow distccd traffic:
Edit Template:Filename in the following three sections:
- BUILDENV has distcc unbanged i.e. without exclamation point.
- Adjust the MAKEFLAGS variable to correspond to the number of
- Uncomment the DISTCC_HOSTS line and add the IP addresses of the servers (slaves) then a slash and the number of threads they are to use. The subsequent IP address/threads should be separated by a white space. This list is ordered from most powerful to least powerful (processing power).
Example using relevant lines:
BUILDENV=(distcc fakeroot color !ccache !check) MAKEFLAGS="-j11" DISTCC_HOSTS="192.168.0.2/5 192.168.0.3/3 192.168.0.4/3"
Note that the sum of individual values specified for the max threads per server should equal less than the value defined in MAKEFLAGS. In the above example, this is 5+3+3=11. If users specify more than this sum, the extra theoretical thread will be blocked by distcc and appear as such in monitoring utils such as distccmon-text described below.
If users wish to use distcc through SSH, add an "@" symbol in front of the IP address in this section. If key-based auth is not setup on the systems, set the DISTCC_SSH variable to ignore checking for authenticated hosts, i.e. DISTCC_SSH="ssh -i"
Start the distcc daemon on every participating machine:
# rc.d start distccd
If having distccd run at boot up, add it to the DAEMONS array in Template:Filename.
Compile via makepkg as normal.
Progress can be monitored via several methods.
- tailing log file
Invoke distccmon-text to check on compilation status:
$ distccmon-text 29291 Preprocess probe_64.c 192.168.0.2 30954 Compile apic_noop.c 192.168.0.2 30932 Preprocess kfifo.c 192.168.0.2 30919 Compile blk-core.c 192.168.0.2 30444 Compile block_dev.c 192.168.0.3 30904 Compile compat.c 192.168.0.3 30891 Compile hugetlb.c 192.168.0.3 30458 Compile catalog.c 192.168.0.4 30496 Compile ulpqueue.c 192.168.0.4 30506 Compile alloc.c 192.168.0.4
One can have this program run continuously by using watch or by appending a space followed by interger to the command which corresponds to the number of sec to wait for a repeat query:
$ watch distccmon-text
$ distccmon-text 2
One can also simply tail Template:Filename on daemon:
# tail -f /var/log/messages.log
Limit HDD/SDD usage
By default, distcc creates a $HOME/.distcc which stores transient relevant info as it serves up work for nodes to compile. Create a directory named .distcc in RAM such as /dev/shm and soft link to it in $HOME. This will avoid needless HDD read/writes and is particularly important for SSDs.
$ mv ~/.distcc /dev/shm $ ln -s ~/.distcc /dev/shm/.distcc
One only needs to have Template:Filename re-create this directory on a reboot (the soft link will remain until it is manually removed like any other file):
su -c "mkdir /dev/shm/.distcc" USERNAME
Adjust log level
By default, distcc will log to Template:Filename as it goes along. One trick (actually recommended in the distccd manpage) is to log to an alternative file directly. Again, one can locate this in RAM via /dev/shm. Another trick is to lower to log level of minimum severity of error that will be included in the log file. Useful if only wanting to see error messages rather than an entry for each connection. LEVEL can be any of the standard syslog levels, and in particular critical, error, warning, notice, info, or debug.
Both of these lines are to be appended to DISTCC_ARGS in Template:Filename
DISTCC_ARGS="--user nobody --allow 192.168.0.0/24 --log-level error --log-file /dev/shm/distccd.log"