On 24 June 2015 at 14:50, Adhemerval Zanella <adhemerval.zane...@linaro.org> wrote: > I tried some of author advices getting very good results. Basically I > moved to optimized clang build, changed to gold linker and used another > memory allocator than system glibc one. Results in build time for all > the clang/llvm toolchain is summarized below (my machine is a i7-4510U, > 2C/4T, 8GB, 256GB SSD):
Optimised + no-assertion builds of clang are in general 2/3 of gcc's build times. > Gold linker also shows a *much* less RSS usage, I am able to fully use make > -j4 > while linking in 8GB without issue any swapping. BFD uses more than 2GB of RAM per process when linking statically debug versions of LLVM+Clang. What I did was to use gold and enable shared libraries in the debug version. > 1. Change from libc to tcmalloc showed me a 3-4% improvement. I tried > jemalloc, > but tcmalloc is faster. I am using currently system version 2.2, but I > have > pushed an aggressive decommit patch to enable as default for 2.4 that might > show lower RSS and latency (I will check it later). Using Ninja generally makes that edge disappear, because it builds a lot less files than make would. I also recommend ccache if you're using gcc, but with Clang it tends to generate some bogus warnings. > 2. First I try to accelerate my build by offloading compilation using distcc. > Results were good, although the other machine utilization (i7, 4C/8T, 8GB) > showed mixes cpu utilization. The problem was linking memory utilization > using ld.bfd, which generates a lot of swapping with higher job count. I > will try using distcc with clang. Distcc only helps if you use the Ninja "pool" feature on the linking jobs. http://www.systemcall.eu/blog/2013/02/distributed-compilation-on-a-pandaboard-cluster/ Also, I don't want to depend on having a desktop near me, nor distributing jobs across the Internet, so distcc has very limited value. If you have a powerful desktop, I recommend that you move your tree in there, maybe use your laptop as the distcc slave, and export the source/build trees via NFS, Samba or SSHFS. cheers, --renato _______________________________________________ linaro-toolchain mailing list linaro-toolchain@lists.linaro.org https://lists.linaro.org/mailman/listinfo/linaro-toolchain
