The "jobs" script is used to determine the amount of compilation
parallelism on a machine. It attempts to ensure each GCC process has at
least 4 GB of memory per core. However, in the worst case scenario, we
could end up having the GCC processes take up all the system memory,
forcin swapping or OOM killer to kick in. For example, on a 4 core
machine with 16 GB of memory, this worst case scenario seems easy to
trigger in practice.
Fix up the problem by keeping a 1 GB of memory reserve for other
processes and calculating parallelism based on that.
Message-Id: <20200423082753.31162-1-penberg@scylladb.com>
7304a795e5