Re: [PATCH 0/8] gitlab: speed up msys windows jobs with GCC

[Thomas Huth <thuth@redhat.com>]

On 01/08/2023 15.03, Daniel P. Berrangé wrote:
> This is an alternative and/or complementary to Thomas' proposal
> to use CLang with msys:
> 
>    https://lists.gnu.org/archive/html/qemu-devel/2023-07/msg05402.html
> 
> First of all, the current msys installer we're using is over 12
> months out of date. Thus after running the install, pacman then
> replaces most of what we've just installed with new downloaded
> content. Using the most update installer cuts 3+1/2 minutes off
> the msys install time - 7 minutes becomes 3+1/2.
> 
> Secondly, QEMU defaults to compiling with -O2 and this is more
> computationally expensive for GCC. Switching to -O0 drops the
> build time from 60 minutes down to 45 minutes.
> 
> Thirdly, including debug symbols also has an overhead, and turning
> that off reduces time still further down to 38 minutes.
> 
> IOW, between all three changes, we can cut approx 25-26 minutes
> off the job execution time, bringing it nicely within the job
> timeout.
> 
> The actually phase of installing the mingw deps still accounts
> for about 10 minutes and has not been optimized.
> 
> Possibly the same trick of -O0 and skipping -g would also help
> the clang alternative Thomas' proposed. If so, that could be
> enough to let us enable more features / targets during the
> msys build.

I really like the idea! And I guess my idea with Clang needs some more work 
'til it is acceptable, so let's go with your idea for now to fix the timeout 
problem in the CI ... we can still optimize later with Clang in case we 
found a good solution for that ms_struct problem...

  Thomas