On Sat, Aug 22, 2020 at 06:04:48PM -0300, Giuliano Belinassi wrote: > Hi, Josh > > On 08/21, Josh Triplett wrote: > > On Thu, Aug 20, 2020 at 07:00:13PM -0300, Giuliano Belinassi wrote: > > > This patch series add a new flag "-fparallel-jobs=" to control if the > > > compiler should try to compile the current file in parallel. > > [...] > > > Bootstrapped and Regtested on Linux x86_64. > > > > > > Giuliano Belinassi (6): > > > Modify gcc driver for parallel compilation > > > Implement a new partitioner for parallel compilation > > > Implement fork-based parallelism engine > > > Add `+' for Jobserver Integration > > > Add invoke documentation > > > New tests for parallel compilation feature > > > > Very nice! > > Thank you for your interest in this :) > > > > > I'm interested in testing this on a highly parallel system. What > > baseline do these patches apply to? They don't seem to apply to GCC > > trunk. > > Hummm, this was supposed to work on trunk out of the box. However, > there is a high probability that I messed up something while rebasing. > I will post a version 2 of it when I get more comments and when I fix > the Makefile issue that Joseph pointed out in other e-mail. > > If you want to test it on a high parallel system, I think it will be > cool to see how it behaves also when --param=promote-statics=1, as it > increases parallelism opportunity. :)
I plan to try several variations, including that. I'd like to see how it affects the performance of Linux kernel builds. > > Also, I tried to bootstrap the current tip of the devel/autopar_devel > > branch, but ended up with compiler segfaults that all look like this: > > ../../gcc/zlib/compress.c:86:1: internal compiler error: Segmentation fault > > 86 | } > > | ^ > > Well, there was once a bug in this branch when compiling with -flto that > caused the assembler output file not to be properly initialized early > enough, resulting in LTO LGEN stage writing into a invalid FILE pointer. > I fixed this during rebasing but I forgot to push to the autopar_devel > branch. In any case, I just pushed the recent changes to autopar_devel > which fix this issue. That might explain the problem; I had tried to build gcc with the bootstrap-lto configuration. > In any case, -fparallel-jobs= should NOT be used together with -flto. > Although I used part of the LTO engine for development of this feature, > they are meant for distinct things. I guess I should give a warning > about that in next version :) Interesting. Is that something that could change in the future? I'd like to be able to get some parallelism when creating the object files, and then more parallelism when doing the final LTO link. > Also, I just tested bootstrap with > > ../gcc/configure --disable-multilib --enable-languages=c,c++ > > on x86_64 linux and it is working. I'd used --enable-multilib, and --enable-languages=c,c++,lto . Would that be expected to work? Thanks, Josh
