On Mon, 25 May 2009, Pekka J Enberg wrote:diff --git a/init/main.c b/init/main.c
index 33ce929..fb0e004 100644
@@ -576,6 +576,22 @@ asmlinkage void __init start_kernel(void)
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
+ printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
+ parse_args("Booting kernel", static_command_line, __start___param,
+ __stop___param - __start___param,
+ * Set up kernel memory allocators
So what strikes me is a question:
- why do we want to do pidhash_init and vfs_caches_init_early() so early?
Yes, pidhash_init() now uses alloc_bootmem. It's an allocation that is not trivially small, but it's not humongous either (max 4096 hash list heads, one pointer each).
And vfs_caches_init_early() is actually doing some rather strange things, like doing a "alloc_large_system_hash()" but not unconditionally: it does it in the "late" initialization too, if not done early. inode_init_early does soemthing very similar (ie a _conditional_ early init).
So none of this seems to really get a huge advantage from the early init. There seems to be some subtle NUMA issues, but do we really want that? I get the feeling that nobody ever wanted to do it early, and then the NUMA people said "I don't wnt to do this early, but I don't want to touch the non-NUMA case, so I'll do it early for non-numa, and late for numa".
I'm also not entirely sure we really need to do vmalloc_init() that early, but I dunno. It also uses alloc_bootmem().