speed up making the world

Rebuilding world

• Run in single user mode.

• Put the /usr/src and /usr/obj directories on separate file systems held on separate disks. If possible, put these disks on separate disk controllers.

• Better still, put these file systems across multiple disks using the ccd(4) (concatenated disk driver) device.

• Turn off profiling (set “NO_PROFILE=true” in /etc/make.conf). You almost certainly do not need it.

• Also in /etc/make.conf, set CFLAGS to something like -O -pipe. The optimization -O2 is much slower, and the optimization difference between -O and -O2 is normally negligible. -pipe lets the compiler use pipes rather than temporary files for communication, which saves disk access (at the expense of memory).

• Pass the -jn option to make(1) to run multiple processes in parallel. This usually helps regardless of whether you have a single or a multi processor machine.

• The file system holding /usr/src can be mounted (or remounted) with the noatime option. This prevents the file system from recording the file access time. You probably do not need this information anyway.

  # mount -u -o noatime /usr/src
  

  Warning: The example assumes /usr/src is on its own file system. If it is not (if it is a part of /usr for example) then you will need to use that file system mount point, and not /usr/src.

• The file system holding /usr/obj can be mounted (or remounted) with the async option. This causes disk writes to happen asynchronously. In other words, the write completes immediately, and the data is written to the disk a few seconds later. This allows writes to be clustered together, and can be a dramatic performance boost.

  Warning: Keep in mind that this option makes your file system more fragile. With this option there is an increased chance that, should power fail, the file system will be in an unrecoverable state when the machine restarts.

  If /usr/obj is the only thing on this file system then it is not a problem. If you have other, valuable data on the same file system then ensure your backups are fresh before you enable this option.

  # mount -u -o async /usr/obj
  

  Warning: As above, if /usr/obj is not on its own file system, replace it in the example with the name of the appropriate mount point.