On Wed, Sep 24, 2014 at 11:47 PM, Ian Lance Taylor wrote: > On Wed, Sep 24, 2014 at 10:04 AM, Steven Bosscher wrote: >> Are you using -pipe? AFAIR this still isn't the default, even on >> GNU/Linux, but it is typically a lot faster than without. > > Is that true even when TMPDIR is on a ram disk? There's no obvious > reason that it should be true in a parallel build. Using -pipe > effectively constrains communication between the compiler and the > assembler to work in PIPE_BUF blocks. Using TMPDIR introduces no such > constraints, and in a big program a parallel build should obscure the > fact that the compiler and assembler are serialized for each > individual compilation unit.
I've done my most recent timings on a machine that has /dev/md3 mounted on /tmp. That's gcc110 on the compile farm. With/without -pipe made a significant difference. If TMPDIR is a tmpfs or other kind of ram disk, I suppose the benefits would be less (to the point of vanishing). Unfortunately I can't test it... Ciao! Steven