Re: Reporting bugs and bisection

From: Andi Kleen <andi@firstfloor.org>
Date: Apr 16, 2008, 11:02 UTC
Message-ID: <87mynu5agq.fsf@basil.nowhere.org>
In-Reply-To: <4805C199.2090702@davidnewall.com>

David Newall <davidn@davidnewall.com> writes:

>
> And I'd rather be able to see that that person introduced 100 bugs than
> to have no idea.   As has been said before, the current situation rewards
> people for sloppy work.

A common issue in the kernel is code who works with a wide range of hardware and firmware with varying quality. The original code is written to spec but then in the real world the hardware and firmware has all kinds of interesting quirks not quite matching the spec that need additional updates to handle. I don't think it's fair to say in this case the original developer was sloppy.

Then there is also code which is just hard to tune. Examples for this are the CPU scheduler and the VM, but also other areas. They have to handle a lot of different workloads with often subtle side effects. Lots of people have put a lot of excellent work into tuning these subsystems as users report issues with their workloads. Would you say the original developers were sloppy? I don't think that would be a fair description. Some problems are just hard and need many iterations to get right. And then often also the requirements change over time and need further updates.

There are more such examples in kernel.

Grading programers is a hard problem and I don't think the software industry has really solved it so far, even though there was a lot of effort trying to do it over several decades. I doubt it will be solved for the Linux kernel either.

-Andi