* Arnd Bergmann <arnd@xxxxxxxx> wrote: > > If we include comments & line-markers then the bloat goes up by another > > ~2x: > > > > kepler:~/mingo.tip.git> ./st include/linux/sched.h > > #include <linux/sched.h> | LOC: 2,186 | headers: 118 > > kepler:~/mingo.tip.git> ./st include/linux/sched.h > > #include <linux/sched.h> | LOC: 4,092 | headers: 0 > > The metric I've been focusing on is bytes of the preprocessed header, > which is more sensitive to function definitions that get generated from > macros, and I multiply this by the number of inclusions (from scanning > the .file.o.cmd files). It probably helps to have a couple of metrics and > look at all of them occasionally to not miss something important. Actual inclusions don't just depend on .file.o.cmd files though, that won't catch indirect inclusions, right? > In the meantime, I have made some progress on reducing the headers > for arm64, on top of your tree from Jan 8, but I have not looked at > later changes from your side, and I need to work on this a bit more > to ensure this doesn't break other architectures. Sure & great! > For an arm64 allmodconfig build, my additional improvements on top > of yours are significant but not as good as I had hoped for, this > can still improve I hope: > > 5.16-rc8-vanilla 32640 seconds user, 3286 seconds sys > 5.16-rc8-mingo 22990 seconds user, 2304 seconds sys > 5.16-rc8-arnd 19007 seconds user, 1853 seconds sys ~71% build throughput speedup for allmodconfig is very impressive to me. :-) > As my tree builds any randconfig cleanly, [...] Yeah, same here - having a few thousand randconfig build tests is normal for each version: /* This file is auto generated, version 3288 */ #define UTS_MACHINE "x86_64" #define UTS_VERSION "#3288 Fri Jan 14 18:20:14 CET 2022" My testing is mostly concentrated on x86 - but I often test ARM64 randconfig as well. > I keep looking at different configs and find that this has a big impact, > some options end up eliminating most of the benefits until I add further > changes to clean up certain files. This happened with kasan, kprobes, and > lse-atomics for instance. After eliminating all circular includes, I was > also able to revisit my old script to visualize the inclusions, see[1] > for the current arm64 defconfig output. This version uses my arbitrary > metric as font-size, and uses labels for the number of inclusions. This is really nice! I was concentrating on optimizing a generic distro config - which doesn't include the tons of extreme instrumentation measures that allmodconfig includes but production distro kernels rarely do. allmodconfig definitely needs more work, but 71% is a pretty good starting point ... Feel free to send in patches, I can help with the testing too. Thanks, Ingo
