From: Ingo Molnar Sent: November 13, 2018 at 11:30:00 AM GMT > To: Nadav Amit <namit@xxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>, Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>, Michal Marek <michal.lkml@xxxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, H. Peter Anvin <hpa@xxxxxxxxx>, x86@xxxxxxxxxx, linux-kbuild@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH 1/2] Makefile: Fix distcc compilation with x86 macros > > > > * Nadav Amit <namit@xxxxxxxxxx> wrote: > >> Introducing the use of asm macros in c-code broke distcc, since it only >> sends the preprocessed source file. The solution is to break the >> compilation into two separate phases of compilation and assembly, and >> between the two concatanate the assembly macros and the compiled (yet > > s/concatenate > >> not assembled) source file. Since this is less efficient, this >> compilation mode is only used when make is called with the "DISTCC=y" >> parameter. >> >> Note that the assembly stage should also be distributed, if distcc is >> configured using "CFLAGS=-DENABLE_REMOTE_ASSEMBLE". > > It's a bit sad that we regressed distcc performance … I don’t know what the actual impact is, but Logan, who reported the bug says there is an alternative solution for when distcc-pump is used (which presumably would have ~zero performance degradation). distcc is really fragile IMHO - it’s enough that it finds what looks like two source files in the compiler command arguments for it to fall back to local compilation. [ In this regard, the distcc-pump solution would *not* work if distcc is built with support for distributed assembly, since it will consider the .s file as a second source file. ] >> +# If distcc is used, then when an assembly macro files is needed, the >> +# compilation stage and the assembly stage need to be separated. Providing >> +# "DISTCC=y" option enables the separate compilation and assembly. > > Let's fix the various typos: > >> +# If distcc is used, and when assembly macro files are needed, the >> +# compilation stage and the assembly stage needs to be separated. >> +# Providing the "DISTCC=y" option enables separate compilation and >> +# assembly. That’s grammar, not typos ;-) Sorry for that - I will fix it an send v2 (as well as the whitespace noise). Regards, Nadav
