[dm-devel] [PATCH 05/11] block: get rid of the trace rq insert wrapper

[hch at lst.de]

On Fri, Jul 03, 2020 at 11:29:25PM +0000, Chaitanya Kulkarni wrote:
> Christoph,
> 
> On 6/29/20 4:44 PM, Chaitanya Kulkarni wrote:
> > Get rid of the wrapper for trace_block_rq_insert() and call the function
> > directly.
> > 
> > Signed-off-by: Chaitanya Kulkarni<chaitanya.kulkarni at wdc.com>
> > ---
> 
> Can we re-consider adding this patch ? here are couple of reasons:-
> 
> 1. Increase in the size of the text region of the object file:-
> 
>     By adding the trace header #include <trace/events/block.h>
>     in io-scheduler where it is calling trace_block_rq_insert()
>     increases the size of the text region of the object file
>     kyber(+215) & bfq (+317) [1].

You really shouldn't have both loaded, never mind used at the same
time.  It also avoid a function call for the scheduler fast path.

> 2. Mandatory io-sched built-in kernel compilation:-
> 
>     When testing with a different io-sched KConfig options ("*" vs "M"),
>     when kyber and bfq compilation option set to "M" having this patch
>     reports error[2].

See EXPORT_TRACEPOINT_SYMBOL_GPL.