Re: [PATCH V2] xfs: introduce CONFIG_XFS_WARN

Eric Sandeen
2013-04-25T00:21:24Z

On 4/24/13 5:58 PM, Dave Chinner wrote:
> On Wed, Apr 24, 2013 at 01:39:52PM -0500, Chandra Seetharaman wrote:
>> Hi Dave,
>>
>> Since this solution is for production environment, would it be valuable
>> to have a sysctl variable to allow enabling/disabling XFS_WARN, as
>> opposed to needing to recompile the module afresh ?
>
> The idea is that distros enable it on the debug kernel packages
> rather than using CONFIG_XFS_DEBUG=y. Hence if someone has a
> problem, they just install the debug kernel and they get all this
> additional checking.
>
> There are roughly 1700 ASSERT statements in the XFS code, so
> compiling them in unconditionally is a lot of extra code. Adding a
> sysctl to make them conditional adds as many branches into the code
> than in 99.99999% of calls are never going to evaluate as true. The
> convenience of a sysctl is more than outweighed by the additional
> overhead for the majortiy of people that don't need to diagnose
> problems on their system.
>
> Hence I don't think the overhead of unconditionally compiling in
> ASSERT checks is worth while for the majority of users, especially
> as most distros ship a debug kernel for exactly this purpose....

I agree. kernel-debug, or whatever your distro does similarly,
is the right use for this code.

-Eric

> Cheers,
>
> Dave.