Re: [PATCH v3 1/8] ftrace: Add DYNAMIC_FTRACE_WITH_CALL_OPS

[Wangshaobo (bobo)]

在 2023/1/30 18:25, Mark Rutland 写道:
> On Sat, Jan 28, 2023 at 04:46:48PM +0800, Wangshaobo (bobo) wrote:
> > 锟斤拷 2023/1/23 21:45, Mark Rutland 写锟斤拷:
> > > +config DYNAMIC_FTRACE_WITH_CALL_OPS
> > > +	def_bool y
> > > +	depends on HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
> > > +
> > Hi Mark,
>
> Hi,
>
> > I have test your patches and it looks fine with my sample module,
>
> Thanks for testing!
>
> > but here setting DYNAMIC_FTRACE_WITH_CALL_OPS to y immutably may increase the
> > .text section size by 5% or more, how about making this to optional^^
>
> We could consider making this optional. I had not made this optional so far as
> in the future I'd like to make this the only implementation of ftrace on arm64
> (once we can drop the old mcount version, and once we've sorted out the
> incompatibility with CFI). In the mean time, it probably makes sense to have
> the option at least to enable testing of each of the two forms.
>
> Is your concern that the overall kernel image size is larger, or do you care
> specifically about the size of the .text section for some reason?
>
> Thanks,
> Mark
Embedded devices may pay more attention to Image size, and which may 
also indirectly affects performance, for more reason, I think making 
sense to have the option for testing is more important.

-- Wang ShaoBo
> > -- Wang ShaoBo
> > >    config DYNAMIC_FTRACE_WITH_ARGS
> > >    	def_bool y
> > >    	depends on DYNAMIC_FTRACE
> > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> > > index 442438b93fe9..e634b80f49d1 100644