Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH 3/4] module: use a structure to encapsulate layout. | Date | Tue, 10 Nov 2015 12:11:46 +1030 |
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Peter Zijlstra <peterz@infradead.org> writes: > On Mon, Nov 09, 2015 at 02:53:56PM +1030, Rusty Russell wrote: >> diff --git a/kernel/module.c b/kernel/module.c >> index 14b224967e7b..a0a3d6d9d5e8 100644 >> --- a/kernel/module.c >> +++ b/kernel/module.c >> @@ -108,13 +108,6 @@ static LIST_HEAD(modules); >> * Use a latched RB-tree for __module_address(); this allows us to use >> * RCU-sched lookups of the address from any context. >> * >> - * Because modules have two address ranges: init and core, we need two >> - * latch_tree_nodes entries. Therefore we need the back-pointer from >> - * mod_tree_node. > > We still have the back-pointers, so removing all of that seems a little > excessive.
Well, I thought about filling the hole with a "am_init" flag, and putting the layouts in a [2] array, but seemed too cutesy.
>> - * >> - * Because init ranges are short lived we mark them unlikely and have placed >> - * them outside the critical cacheline in struct module. > > This information also isn't preserved.
Ah yeah, Intel still use 64-byte cachelines. Still, this comment covers what we actually care about:
+#ifdef CONFIG_MODULES_TREE_LOOKUP +/* Only touch one cacheline for common rbtree-for-core-layout case. */ +#define __module_layout_align ____cacheline_aligned +#else +#define __module_layout_align +#endif
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Thanks! Rusty.
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