Re: [PATCH RFC rdma-core 1/3] util: Add common code for provider debug

[Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>]

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On Wed, Jan 18, 2017 at 09:44:44AM -0700, Jason Gunthorpe wrote:
> On Wed, Jan 18, 2017 at 07:31:30AM +0200, Leon Romanovsky wrote:
> > > +#define PRINT_ERR(fmt, ...)								\
> > > +do {											\
> > > +	fprintf(stderr, "[%s:%d]" fmt, __func__, __LINE__, ##__VA_ARGS__);		\
> > > +} while (0)
> > > +
> > > +#define PRINT_DBG(dbg_mask, dbg_level, fmt, ...)					\
> > > +do {											\
> > > +	if ((rdma_dbg_mask & dbg_mask) && (rdma_dbg_level >= dbg_level))		\
> > > +		fprintf(stderr, "[%s:%d]" fmt, __func__, __LINE__, ##__VA_ARGS__);	\
> > > +} while (0)
> > > +
> > > +#define LOG_DBG(dbg_fp, dbg_mask, dbg_level, fmt, ...)					\
> > > +do {											\
> > > +	if ((rdma_dbg_mask & dbg_mask) && (rdma_dbg_level >= dbg_level))		\
> > > +		fprintf(dbg_fp, "[%s:%d]" fmt, __func__, __LINE__, ##__VA_ARGS__);	\
> > > +} while (0)
> > > +
> > > +#define LOG_DBG_FLUSH(dbg_fp, dbg_mask, dbg_level, fmt, ...)				\
> > > +do {											\
> > > +		LOG_DBG(dbg_fp, dbg_mask, dbg_level, fmt, ##__VA_ARGS__);		\
> > > +		if (dbg_fp != stderr)							\
> > > +			fflush(dbg_fp);							\
> > > +} while (0)
> >
> > IMHO, these macros should be inline functions, and better to avoid global variables.
>
> It is more expensive at the call site to inline something that calls
> via va_args than via ..., so these should remain as macros.

These macros/functions need to be compiled in for DEBUG mode only, in
such case you can pay extra CPU cycles.

>
> When doing this people generally like the 'if' test to be outside, for
> performance.
>
> I'm still not sure about these.. Why do we need print & log? I think
> there should only be one. Providers should not print to stderr unless
> the user asks for debugging.
>
> Jason
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