performance regressions

[Richard Eisenberg]

I pushed my supposed fix yesterday morning, as I emailed out the "Fixed, hopefully" note.

Of course, I now see that it wasn't a full fix.

This is all most assuredly my fault. However, I also feel that elements of the infrastructure failed me somewhat, making this error easier for me to commit:
- Travis has not picked up on these errors.
- Harbormaster has seemed unreliable, finding spurious compile-time errors sometimes, and sometimes just failing to test code that it sees. For example, when I pushed Diff 1901 to D546, Harbormaster never even attempted. Also, when I pushed my "fix", commit 3ec9391711, Harbormaster also skipped, as viewable here: https://phabricator.haskell.org/diffusion/GHC/

So, after pushing yesterday morning, I didn't get any email from Harbormaster saying that it failed, so I thought my fix was indeed a fix. Because my local build was a devel2 build (and that I had only about 20 minutes to work), I was unable to test locally -- all I could tell is that my fix lowered the numbers (as verified by ghcspeed).

Having a weekend full of plans, there wasn't really any opportunity for me to do the work necessary to figure out what's going on. It will be first on my docket tomorrow.

I suppose one lesson here is that I shouldn't push anything at all non-trivial on a Friday afternoon. But I also hope we can either improve the infrastructure (of course, it's *much* better than it was months ago!) or have realistic expectations of what we can expect from the infrastructure (e.g., trust Harbormaster/Travis when seeking feedback, but always validate locally before actually pushing to master).

More tomorrow,
Richard

On Dec 14, 2014, at 3:47 PM, Joachim Breitner <mail at joachim-breitner.de> wrote:

> Hi,
> 
> Am Samstag, den 13.12.2014, 10:55 -0500 schrieb Richard Eisenberg:
>> Fixed, hopefully!
> 
> Mitigated, but still a regression:
> 
> http://ghcspeed-nomeata.rhcloud.com/timeline/?exe=2&base=2%2B68&ben=tests%2Falloc%2FT9872a&env=1&revs=50&equid=on#
> 
> Is that now a level that we’ll have to live with, or is it still
> unexpectedly high?
> 
> Greetings,
> Joachim
> 
> -- 
> Joachim “nomeata” Breitner
>  mail at joachim-breitner.de • http://www.joachim-breitner.de/
>  Jabber: nomeata at joachim-breitner.de  • GPG-Key: 0xF0FBF51F
>  Debian Developer: nomeata at debian.org
>