[Nix-dev] Parallel building support, 2nd attempt

[Eelco Dolstra]

Hi,

On 06/23/2010 04:40 PM, Peter Simons wrote:

> support for parallel builds is now in stdenv-updates. The only major change
> relative to the diff I posted is that the generic builder can auto-detect the
> number of available cores. To enable that feature, "build-cores" must be set to
> "0", "guess" or "auto". The same applies to the "--cores" command line argument
> (and, yes, it does work for nix-store, nix-build, and nix-env).

I don't really like the word "cores" because it's rather hardware-specific.
(Yes, this is a bikeshed issue.)  We don't really care whether processes/threads
run on different cores, CPUs, hyperthreading cores or whatever.  Indeed, even on
a single-core machine, parallel builds may speed things up because one process
can run while another is waiting for I/O.  The intended semantics of this option
is to indicate the maximum number of parallel processes or threads that a
builder should use.   So a more precise name would be
"--max-internal-parallelism" but that's rather wordy, and "--max-jobs" is
already taken :-)

Any suggestions for a short name?

BTW, strictly speaking we don't need `--cores' since you can also use `--option
build-cores N'.

-- 
Eelco Dolstra | http://www.st.ewi.tudelft.nl/~dolstra/