Re: Progress indicator when (slowly) mounting a btrfs filesystem?

["Austin S. Hemmelgarn" <ahferroin7@gmail.com>]

On 2016-02-01 09:03, Christian Rohmann wrote:
> Hey Chris,
>
> On 01/28/2016 12:47 AM, Chris Murphy wrote:
>> Might be a bug, but more likely might be a lack of optimization. If it
>> eventually mounts without errors that's a pretty good plus. Lots of
>> file systems can't handle power failures well at all.
>
> So what and how should I go about profiling such a long running mount in
> order to help finding point where optimization is needed the most then?
It would probably require some work with perf and ftrace, which means 
you likely need to build a special kernel just for testing, and then 
generate an ideally clean-room like environment (whatever hosting, plus 
userspace, plus a consistent filesystem image that you can reuse for 
each test, etc).

Kernel profiling is a decidedly non-trivial task, and is not something I 
would recommend somebody try unless both:
a) They already have a working knowledge of kernel internals, or are 
willing to learn.
b) They have the time and resources to do it right in a reproducible manner.