[LLVMdev] RFC: Upcoming Build System Changes

[John Criswell]

Dear All,

We have a new 32 core machine, so I ran some numbers.  These results are 
for compiling all of LLVM and Clang in a Debug build from scratch.  The 
first number is the -j argument to make, and the rest is the result of 
the bash builtin time command.

2:  1612.950u 161.293s 15:04.92 196.0%       0+0k 0+0io 0pf+0w

4:  1624.101u 164.121s  8:00.74 371.9%       0+0k 0+0io 0pf+0w

8:  1657.272u 176.211s  4:35.31 665.9%       0+0k 0+0io 0pf+0w

16: 1681.512u 189.706s  2:48.96 1107.4%      0+0k 0+0io 0pf+0w

32: 1698.817u 209.073s  2:02.88 1552.6%      0+0k 0+0io 0pf+0w


The processors are Intel(R) Xeon(R) CPU E7- 8837  @ 2.67GHz.

Note that I had two other processes running, so 2 cores were unavailable 
throughout the -j32 build.

I did not use CMake but the standard autoconf + Makefile build.

Not sure if this helps, but here it is, for what it's worth.

-- John T.