[llvm-dev] buildbot failure in LLVM on clang-native-arm-cortex-a9

[Philip Reames via llvm-dev]

On 08/26/2015 09:27 AM, Renato Golin via llvm-dev wrote:
> On 26 August 2015 at 17:21, David Blaikie <dblaikie at gmail.com> wrote:
>> (oh, and add long cycle times to the list of issues - people do have a
>> tendency to ignore bots that come back with giant blame lists & no obvious
>> determination as to who's patch caused the problem, if any)
> Yes, but remember, not all hardware is as fast as a multi-core Xeon
> server. Build times can't always be controlled.
No, but there are many known partial solutions.  We can explore some of 
them if build time is the only issue.

Some options (I don't know which if any have already been explored)
- Kick off builds on slow bots at revisions which have passed a fast bot
- Overlap builds on different pieces of hardware so that revision ranges 
are smaller (i.e. "that change was in the previous build and didn't 
fail, so it can't be that")
- Build incrementally with occasional clean builds at already known good 
revisions (or for failure recovery)
- Separate build and test.  Cross build on a faster machine then 
transfer the binaries to a slower test machine.  Run only a build on the 
slow machine.  (i.e. decrease latency of build+test to latency of build 
OR test)
- Consider using an emulator on a faster machine to get initial 
results.  Only kick off builds on hardware for changes that pass the 
emulator.  (This is a particular variant of (1) above.)
>
> But I agree with you on all accounts. The bot owner should bear the
> responsibility of his/her own unstable bots. If it brings less value
> than it adds cost to the community, it should be moved to a separate
> buildmaster that doesn't email people around, but can be accessed, so
> the owner can point breakages to devs.
>
> cheers,
> --renato
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