[Ksummit-discuss] [topic proposal] tracepoints and ABI stability warranties

[Rik van Riel]

On Wed, 2016-09-07 at 09:30 -0600, Shuah Khan wrote:
> On Tue, Sep 6, 2016 at 11:30 PM, Andy Lutomirski <luto at kernel.org>
> wrote:
> > 
> > I wouldn't mind a policy that tracepoints are simply never
> > stable.  Maybe we
> > should even deliberately change them periodically to drive the
> > point home.
> > 
> > The kernel should be able to have a debug API that is genuinely for
> > *debugging* and doesn't freeze the underlying implementation.
> Agreed. Tracepoints and events provide a powerful tool in debug
> certain class
> of problems (races and performance problems) where traditional debug
> methods
> such as CONFIG_DEBUG_FOO aren't effective. Trace information includes
> important
> status information on thread status which is helpful in debugging.

From an enterprise distro (and user) point of view,
it is important to be able to debug a kernel that
is running on a production system (and developed
some problem after a month of running), without
having to reboot into a special "debug kernel".

Being able to just fire up a tracer debugging
script that can identify intermittent problems
is an invaluable tool in making the kernel better
for our users.

Hamstringing our ability to make the kernel better,
in order to keep the debugging ABI stable, is
shooting ourselves (and our users) in the foot.

-- 
All rights reversed
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