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GNU make options (was Re: if-conversion ...)
- To: amylaar at cygnus dot co dot uk (Joern Rennecke)
- Subject: GNU make options (was Re: if-conversion ...)
- From: Joe Buck <jbuck at possibly dot synopsys dot com>
- Date: Wed, 10 May 2000 14:22:36 -0700 (PDT)
- Cc: schwab at suse dot de (Andreas Schwab), rth at cygnus dot com (Richard Henderson), lucier at math dot purdue dot edu (Brad Lucier), matzmich at cs dot tu-berlin dot de (Michael Matz), gcc at gcc dot gnu dot org
I wrote (re GNU make options)
> > Solution: get make 3.79 and use -j<N>. The GNU make folks should
> > deprecate -l and eventually remove it.
>
> I wouldn't go so far. It seems clear that -l is not useful to make make
> react to the load it creates itself, but you might use it instead or in
> addition to nice to control how much a batch job taxes a system that is
> used for interactive stuff as well.
OK, the combination -j<N> -l <limit> might be useful for that purpose.
But -j without an argument and -l together is a recipe for major problems.
If there is a high degree of parallelism it may result in exhausting
virtual memory, which can be very bad on systems that optimistically
allocate virtual memory (e.g. Linux): the system thrashes severely and
then tries to kill processes at random. This huge load and memory
exhaustion can strike before the load average rises very much.