[Ksummit-2012-discuss] [ATTEND] writeback and kernel testing

Guenter Roeck linux at roeck-us.net
Sat Jun 16 14:07:25 UTC 2012


On Sat, Jun 16, 2012 at 08:44:18PM +0800, Fengguang Wu wrote:
> Greetings,
> 
> I'd like to attend this year's kernel summit.
> 
> I may talk about the technical challenges and trade-offs on writeback and memcg
> and IO controllers with anyone interested, perhaps in some breakout session.
> 
> And I would like a chance to talk about doing kernel tests in a timely fashion:
> whenever one pushes new commits to git.kernel.org, build/boot/stress tests will
> be kicked off and possible errors be notified back to the author within hours.
> 
> This fast develop-test feedback cycle is enabled by running a test
> backend that is able to build 25000 kernels and runtime test 3000
> kernels (assuming 10m boot+testing time for each kernel) each day.
> Just capable enough to outrace our patch creation rate ;-)
> 
> On an average day, 1-2 build errors are caught in the 160 monitored kernel trees.
> 
> The runtime tests are still in active development and I'd like to ask for your
> inputs on best practices and test methodology for every possible subsystems. The
> target is to catch _common_ bugs early, so that a) less people are impacted and
> b) when bisecting a specific bug, it's not confused by unrelated but common bugs.
> 
> I'll need your help and feedback to run this system well. In return, you'll be
> able to take better advantage of it, once got some basic understandings on how
> it runs for you. Hopefully, someday, these diligent machines may bring a little
> happiness to our stressed life. As is the secret of happiness for us kernel
> developers: if a bug is caught and fixed in my own tree, Cheers!  Otherwise if
> the bug has been merged in the upstream tree, OMG, it's out of control and may
> well impact 1000 commits after it.. regrets, sadness, guilty, embarrassments,
> bad commits with my Signed-off-by carved in stone, forever ...
> 
I am running a nightly sequence of builds on my tree, for as many targets as
possible. allyesconfig, allmodconfig, and a large number of randconfigs. That
helps me find most of the problems I had early on, which only show up in some
configurations. That combined with a personal rule to only push code upstream
which has been in my local tree for at least one test cycle helps a lot to avoid
the embarrassment of breaking linux-next or Linus' tree.

I would love to be able to expand that to runtime tests, specifically for
hardware monitoring functionality, but that is a bit more than I can afford
and/or maintain on my own.

Anyway, someone suggested something similar to me a couple of weeks ago, with a
small twist: The ability to submit patches into such a test system before they
are integrated into an upstream kernel. I thought that wasn't feasible, but
maybe it will be at some point, if you can build 25k kernel per day already.

Guenter


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