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[PATCH] Auto size the per cpu area. 

Now for a completely different but trivial approach.
I just boot tested it with 255 CPUS and everything worked.

Currently everything (except module data) we place in
the per cpu area we know about at compile time.  So
instead of allocating a fixed size for the per_cpu area
allocate the number of bytes we need plus a fixed constant
for to be used for modules.

It isn't perfect but it is much less of a pain to
work with than what we are doing now.

AK: fixed warning

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andi Kleen <ak@suse.de>
This commit is contained in:
Eric W. Biederman 2006-09-26 10:52:35 +02:00 committed by Andi Kleen
parent 522e93e3fc
commit ba4d40bb5c
2 changed files with 12 additions and 5 deletions
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7
arch/x86_64/kernel/setup64.c
View File

@ -95,12 +95,9 @@ void __init setup_per_cpu_areas(void)
#endif
/* Copy section for each CPU (we discard the original) */
size = ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES);
#ifdef CONFIG_MODULES
if (size < PERCPU_ENOUGH_ROOM)
size = PERCPU_ENOUGH_ROOM;
#endif
size = PERCPU_ENOUGH_ROOM;
printk(KERN_INFO "PERCPU: Allocating %lu bytes of per cpu data\n", size);
for_each_cpu_mask (i, cpu_possible_map) {
char *ptr;

10
include/asm-x86_64/percpu.h
View File

@ -11,6 +11,16 @@
#include <asm/pda.h>
#ifdef CONFIG_MODULES
# define PERCPU_MODULE_RESERVE 8192
#else
# define PERCPU_MODULE_RESERVE 0
#endif
#define PERCPU_ENOUGH_ROOM \
(ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES) + \
PERCPU_MODULE_RESERVE)
#define __per_cpu_offset(cpu) (cpu_pda(cpu)->data_offset)
#define __my_cpu_offset() read_pda(data_offset)