Date: Wed, 13 Feb 2008 23:26:40 -0800 From: Julian Elischer <julian@elischer.org> To: Bill Moran <wmoran@potentialtech.com> Cc: Ian FREISLICH <ianf@clue.co.za>, Ed Schouten <ed@fxq.nl>, current@freebsd.org Subject: Re: Testing box available. Message-ID: <47B3ED30.2040404@elischer.org> In-Reply-To: <20080213090842.65b240e6.wmoran@potentialtech.com> References: <E1JPBzl-0000jo-Pp@clue.co.za> <20080213073155.GA1340@hoeg.nl> <20080213090842.65b240e6.wmoran@potentialtech.com>
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Bill Moran wrote: > In response to Ed Schouten <ed@fxq.nl>: > >> * Ian FREISLICH <ianf@clue.co.za> wrote: >>> As an aside, a 64 way parallel make buildworld doesn't saturate the CPU. >> I'm not sure, but I think if you do this: >> >> make -j64 <foo> >> >> it only spawns 64 processes to handle the top level make process. This >> would mean we've got a couple of processes doing this: >> >> make -C bin >> make -C lib >> make -C sbin >> make -C usr.bin >> make -C usr.sbin >> >> and the other processes will just quit, because they don't have anything >> to do. Right? :-) > > Basically, -j tells make the _maximum_ number of jobs to run in parallel. > I frequently do -j99, but I've never seen more than about 20. You can't > just look at it for a second, either. Certain parts of the build > process have more parallelism available than others, so you might look > at it at a point where there are only a few. > > If you really want to saturate it, copy the src tree a few times and > start a make -j99 buildworld in all of them simultaneously :D > my memory is that ohk changed make to have a fifo with N (as in -j N) tokens in it and all child makes inherrit this fifo (or get it's name from an environment variable or something) and can only spawn extra makes if they can get a token. When they have finished their work they pu the token back into the fifo.. My memories of this may be somewhat inaccurate however.
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