Re: [Ksummit-discuss] [CORE TOPIC] [nomination] Move Fast and Oops Things

[Randy Dunlap <rdunlap@infradead.org>]

On 05/16/2014 08:04 AM, Chris Mason wrote:
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> On 05/15/2014 10:56 PM, NeilBrown wrote:
>> On Thu, 15 May 2014 16:13:58 -0700 Dan Williams
>> <dan.j.williams@gmail.com> wrote:
>>
>>> What would it take and would we even consider moving 2x faster
>>> than we are now?
>>
>> Hi Dan, you seem to be suggesting that there is some limit other
>> than "competent engineering time" which is slowing Linux "progress"
>> down.
>>
>> Are you really suggesting that?  What might these other limits be?
>>
>> Certainly there are limits to minimum gap between conceptualisation
>> and release (at least one release cycle), but is there really a
>> limit to the parallelism that can be achieved?
> 
> I haven't compared the FB commit rates with the kernel, but I'll
> pretend Dan's basic thesis is right and talk about which parts of the
> facebook model may move faster than the kernel.

Thanks for the summary.

> The facebook is pretty similar to the way the kernel works.  The merge
> window lasts a few days and the major releases are every week, but
> overall it isn't too far away.
> 
> The biggest difference is that we have a centralized tool for
> reviewing the patches, and once it has been reviewed by a specific
> number of people, you push it in.
> 
> The patch submission tool runs the patch through lint and various
> static analysis to make sure it follows proper coding style and
> doesn't include patterns of known bugs.  This cuts down on the review
> work because the silly coding style mistakes are gone before it gets
> to the tool.

Yes, this is very nice.  Reviewers should not be burdened with checking
coding style or common issues or build problems or kconfig problems.
They should just be able to review the merits and correctness of the
patch.  (Yes, that would mean that I would find something different
to do on most days. :)

> When you put in a patch, you have to put in reviewers, and they get a
> little notification that your patch needs review.  Once the reviewers
> are happy, you push the patch in.
> 
> The biggest difference: there are no maintainers.  If I want to go
> change the calendar tool to fix a bug, I patch it, get someone else to
> sign off and push.
> 
> All of which is my way of saying the maintainers (me included) are the
> biggest bottleneck.  There are a lot of reasons I think the maintainer

I have to agree (me included).

> model fits the kernel better, but at least for btrfs I'm trying to
> speed up the patch review process and use patchwork more effectively.
> 
> Facebook controls risk with new features using gatekeepers in the
> code.  That way we can beta test larger changes against an expanding
> group of unsuspecting people without turning it on for everyone at once.
> 
> It's also much easier to accept risk when you have complete control
> over deployment.  facebook.com rolls out twice a day, which is
> basically a stable tree cherry-picked from tip, and there are plenty
> of chances to fix problems.
> 
> Anrdoid/iphone releases can't be controlled the same way, and so they
> have longer testing periods.


-- 
~Randy