[lustre-devel] [PATCH 27/37] lustre: discard lu_ref

[Mike Pershin <mpershin@whamcloud.com>]

On 2/27/19 8:35 AM, Andreas Dilger wrote:
>> On Feb 26, 2019, at 18:17, NeilBrown<neilb@suse.com>  wrote:
>>
>> On Sun, Feb 24 2019, James Simmons wrote:
>>
>>>> struct lu_ref is always an empty structure, and the functions
>>>> which manipulate it do nothing.
>>>> So this is not being tested and so cannot be trusted.
>>>> So remove all these calls and field declarations.
>>> Or we can make lu_ref really work and always test with it :-)
>> We could ... though a lot of the code has been removed already, I was
>> just finishing the job.
>>
>> How useful is this stuff?
>> Has it actually helped to find any bugs?
>> Does it do any run-time checks, or it is just
>> there to help you pull apart a crash-dump?
>>
>> I think there is a real cost in having these extra linkages.  I'd like
>> to be clear what the benefit is.
> I've never used it myself, though I know a few developers that did in the
> past.  That said, most of the time they needed to use it to debug some
> issue they had to push a patch to fix it first...
>
> Mike, Alex, you are most likely to use this code - do you think it is
> still useful?
>
> Cheers, Andreas
> ---
> Andreas Dilger
> Principal Lustre Architect
> Whamcloud
>
I've used that is past to track reference leaks, that can be useful but 
as you said each time I had to fix it first. I think it would be 
reasonable to keep that feature if it is enabled by default on developer 
systems, without that it is not so useful.

Mike