Centos – What does make -jn mean

centosllvmmake

I am trying to install LLVM on my CentOS machine.
In the installation tutorial of LLVM, a flag -jn is specified along with make.

It says to perform make -jn and also says "Choose n such that make doesn’t run in to swap space issue."

What is the use of the -j flag and how can I choose the value of n?

Best Answer

The -j make flag denotes how many threads you want to allot for compiling.

n is, in this case, a place-holder for the number of processes.

The classic rule of thumb is that it's safe to make n = the number of cores your CPU has. So if you are on a dual core machine, you might use -j2, while on an 8-core machine -j8

In practise, I have found that to be a good starting place, but you should probably feel free to experiment a bit and see what works best for you.

Related Solutions

Centos – llvm and clang on CentOS 5 without root permissions

I was able to build clang by following a modified version of steps you took.

# Preliminary:
#  Get source
#  Extract source
#  Set environmental variables

cd /home/avilella/src/llvm/latest
# Clang is expected to be at `tools/clang`.
mv tools/cfe-3.3.src tools/clang
# You should clean before configuring, not after.
make clean
# The missing config.h file is created by the configure script
#  if clang is in the correct location 
./configure --prefix=/home/avilella/src/llvm/latest/llvm
make -j8
make install

Best Answer

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Centos – llvm and clang on CentOS 5 without root permissions

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