Messages in this thread | | | From | Sedat Dilek <> | Date | Tue, 18 Oct 2016 11:28:31 +0200 | Subject | Re: [4.9-rc1] Build-time 2x slower |
| |
On Mon, Oct 17, 2016 at 6:46 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote: > On Mon, Oct 17, 2016 at 9:04 AM, Sedat Dilek <sedat.dilek@gmail.com> wrote: >> >> not sure whom to address on this issue. >> >> I have built Linux v4.9-rc1, v4.8.2 and v4.4.25 kernels (in this >> order) this morning. >> >> Building a Linux v4.8.2 under Linux v4.9-rc1 took two times longer. >> >> As usually I build with 2 parallel-make-jobs. >> This takes approx. 30mins. >> Under Linux v4.9-rc1 it took approx. an hour. > > Hmm. Would you mind just bisecting it? I've not noticed the same thing > on my setup, but to be honest I generally don't time things very > closely because the variation for me tends to be much more along the > lines of "damn, that pull request touched <linux./fs.h> now it's > rebuilding everything" vs "40 seconds to build just the driver that > changed". Most of my builds are the "allmodconfig" builds I do in > between pulls.. > > You can even automate it, since it's going to take some time, using > "git bisect run" and writing a small script that looks at how long it > takes to build the kernel from scratch each time. I'd suggest trying > to write the script using a smaller repository (maybe git itself). The > script would just needs to do a clean rebuild, time it, and have > return success or error based on how long it took. > > The script *might* look something like > > #!/bin/sh > git clean -dqfx > make oldconfig > time -o time-file -f '%e' sh -c "make -j8 > ../output" > # remove fractional seconds > time=$(cat time-file | sed 's/\..*//') > # less than 35 minutes is good? > [ $time -lt $((35*60)) ] > > but I didn't really test that very much. Anyway, you *should* be able > to do something like > > git bisect good v4.8 > git bisect bad v4.9-rc1 > git bisect run ../timing-script > > (put the "timing-script" somewhere _else_ than the kernel sources so > that the "git clean" doesn't remove it - that's what my first silly > test did ;) > > You may have to tweak that script a bit, but I think you get the idea.. >
OK, thanks for confirming the problem. I was not sure if this is a "local" problem.
Your timing-script looks interesting and test... will report.
- Sedat -
| |