Re: [RFC][PATCH] module: Optimize __module_address() using a latched RB-tree

Peter Zijlstra
2015-02-26T17:16:54Z

On Thu, Feb 26, 2015 at 04:55:35PM +0000, Mathieu Desnoyers wrote:
> > Dunno, it seemed like a good a place as any.
>
> My personal coding-style is to put all definitions
> at the top of C files, but I don't know if it's within
> the kernel coding style guide lines or just something
> I'm personally used to. I have no strong opinion here.

So I had all the data structure definition in the C file as well to keep
them private, and then you get into the situation where you can't put it
at the top anyhow.

I further wanted to keep the entire mod_tree stuff together so it can be
easily read. I suppose I can move it to the top of that section, but the
reason I had it there is that it didn't need to exist before that.

> > @@ -269,8 +275,15 @@ struct module {
> > /* Startup function. */
> > int (*init)(void);
> >
> > + /*
> > + * If this is non-NULL, vfree after init() returns
> > + *
> > + * cacheline align here, such that:
> > + * module_init, module_core, init_size, core_size and
> > + * tree_node[0]
> > + * are on the same cacheline.
>
> Fat-fingered newline ? ;)

I made it:

/*
* If this is non-NULL, vfree after init() returns.
*
* Cacheline align here, such that:
* module_init, module_core, init_size, core_size,
* init_text_size, core_text_size and tree_node[0]
* are on the same cacheline.
*/

To be consistent with the other comment.

> > + */
> > + void *module_init ____cacheline_aligned;
> >
> > /* Here is the actual code + data, vfree'd on unload. */
> > void *module_core;
> > @@ -281,6 +294,8 @@ struct module {
> > /* The size of the executable code in each section. */
> > unsigned int init_text_size, core_text_size;
> >
> > + struct module_node tree_node[4];
>
> 4 -> nr_module_addr_latch

Yeah, I dunno, that means moving that enum to the header file, I kinda
liked having it all together in the C file.

What Rusty want though.