On Mon, Oct 17, 2016 at 6:46 PM, Linus Torvalds
> On Mon, Oct 17, 2016 at 9:04 AM, Sedat Dilek <sedat.di...@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
> 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 -