On Thu 2017-03-09 13:16:09, Geert Uytterhoeven wrote: > Hi Pavel, > > On Thu, Mar 9, 2017 at 11:56 AM, Pavel Machek <pa...@ucw.cz> wrote: > > On Thu 2017-03-09 10:38:46, Geert Uytterhoeven wrote: > >> On Wed, Mar 8, 2017 at 10:22 PM, Pavel Machek <pa...@ucw.cz> wrote: > >> > Well, I have fast CPUs, but most of the time they just compile > >> > stuff. Especially bisect is compile-heavy. I suspect going back to > >> > gcc-3.2 would bring me bigger advantages than CPU upgrade... > >> > >> I hope you do use ccache or distcc? > > > > I tried to use distcc before, but it was rather hard to maintain. No > > ccache here. Hmm. I guess ccache really makes sense for bisect. > > Yes it does. So if you're not using it yet, do the below, today, not tomorrow. > > If your distro supports it, prepend /usr/lib/ccache/ to your $PATH. > Create symlinks from the names of your favorite cross-compilers > to /usr/bin/ccache, and make sure they are early in your $PATH. > > That's it! Enjoy!
Hmm. Installed, and seems to work. OTOH, compilation now seems to produce 2-3MB/sec writing on spinning rust, and CPUs are no longer fully loaded. (make -j 7 on 2 core HT machine). Any io load sends the CPU utilization to cca 50% range... Compilation goes up from 9:13 to 11:40... to 23 minutes depending on situation. I guess it is still worth it for the bisect, but it looks like ccache really needs an ssd. On the other hand, switching to -O1 is really easy, and gets 15% or so improvement. Hmm. And killing chromium matters a lot for a compile time. I hate modern web :-(. Best regards, Pavel --- a/Makefile +++ b/Makefile @@ -639,9 +639,9 @@ ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE KBUILD_CFLAGS += -Os $(call cc-disable-warning,maybe-uninitialized,) else ifdef CONFIG_PROFILE_ALL_BRANCHES -KBUILD_CFLAGS += -O2 $(call cc-disable-warning,maybe-uninitialized,) +KBUILD_CFLAGS += -O1 $(call cc-disable-warning,maybe-uninitialized,) else -KBUILD_CFLAGS += -O2 +KBUILD_CFLAGS += -O1 endif endif -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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