Re: [dpdk-dev] [PATCH] examples/distributor: fix missing "; " in debug macro

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2015-06-08 11:58, Bruce Richardson:
> On Fri, Jun 05, 2015 at 10:45:04PM +0200, Thomas Monjalon wrote:
> > It shows that such dead code is almost never tested.
> > It would be saner if this command would return no result:
> > 	git grep 'ifdef.*DEBUG' examples
> > 		examples/distributor/main.c:#ifdef DEBUG
> > 		examples/l3fwd-acl/main.c:#ifdef L3FWDACL_DEBUG
> > 		examples/l3fwd-acl/main.c:#ifdef L3FWDACL_DEBUG
> > 		examples/l3fwd-acl/main.c:#ifdef L3FWDACL_DEBUG
> > 		examples/l3fwd-acl/main.c:#ifdef L3FWDACL_DEBUG
> > 		examples/packet_ordering/main.c:#ifdef DEBUG
> > 		examples/vhost/main.c:#ifdef DEBUG
> > 		examples/vhost/main.h:#ifdef DEBUG
> > 		examples/vhost_xen/main.c:#ifdef DEBUG
> > 		examples/vhost_xen/main.h:#ifdef DEBUG
> > 
> > There is no good reason to not use CONFIG_RTE_LOG_LEVEL to trigger debug build.
> > 
> I agree and disagree. 
> 
> I agree it would be good if we had a standard way of setting up
> a DEBUG build that would make it easier to test and pick up on this sort of things.
> 
> I disagree that the compile time log level is the way to do this. The log level
> at compile time specifies the default log level only, the actual log level is
> controllable at runtime. Having the default log level also affect what kind of
> build is done, e.g. with -O0 rather than -O3, introduces an unnecessary dependency.
> Setting the default log level to 5 and changing it to 9 at runtime should be
> the same as setting the default to 9.

Setting CONFIG_RTE_LOG_LEVEL to 9 means we don't care about performance
degradation due to debug log branches. So it is necessarily a debug build.
Then the default log level must be set by the application.
The EAL default set from CONFIG_RTE_LOG_LEVEL is a last chance default in
case the application doesn't care about it.

Maybe it won't convince you but anyway, it's not important here because the
example applications don't use the DEBUG flag for anything else than the logs.
That's why I think these flags must be removed.
Please check "git grep 'ifdef.*DEBUG' examples".