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[IA64] fix personality(PER_LINUX32) performance issue 

The patch aims to fix a performance issue for the syscall
personality(PER_LINUX32).

On IA-64 box, the syscall personality (PER_LINUX32) has poor performance
because it failed to find the Linux/x86 execution domain. Then it tried
to load the kernel module however it failed always and it used the default
execution domain PER_LINUX instead. Requesting kernel modules is very
expensive. It caused the performance issue. (see the function
lookup_exec_domain in kernel/exec_domain.c).

To resolve the issue, execution domain Linux/x86 is always registered in
initialization time for IA-64 architecture.

Signed-off-by: Xiaolan Huang <xiaolan.huang@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
wifi-calibration
Huang, Xiaolan 2008-05-15 10:18:41 +08:00 committed by Tony Luck
parent 3fb2c74ee2
commit 839052d27e
2 changed files with 25 additions and 10 deletions
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10
arch/ia64/ia32/ia32_support.c
View File

@ -15,7 +15,6 @@
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/personality.h>
#include <linux/sched.h>
#include <asm/intrinsics.h>
@ -29,7 +28,6 @@
extern int die_if_kernel (char *str, struct pt_regs *regs, long err);
struct exec_domain ia32_exec_domain;
struct page *ia32_shared_page[NR_CPUS];
unsigned long *ia32_boot_gdt;
unsigned long *cpu_gdt_table[NR_CPUS];
@ -240,14 +238,6 @@ ia32_cpu_init (void)
static int __init
ia32_init (void)
{
ia32_exec_domain.name = "Linux/x86";
ia32_exec_domain.handler = NULL;
ia32_exec_domain.pers_low = PER_LINUX32;
ia32_exec_domain.pers_high = PER_LINUX32;
ia32_exec_domain.signal_map = default_exec_domain.signal_map;
ia32_exec_domain.signal_invmap = default_exec_domain.signal_invmap;
register_exec_domain(&ia32_exec_domain);
#if PAGE_SHIFT > IA32_PAGE_SHIFT
{
extern struct kmem_cache *ia64_partial_page_cachep;

25
arch/ia64/mm/init.c
View File

@ -719,3 +719,28 @@ out:
EXPORT_SYMBOL_GPL(remove_memory);
#endif /* CONFIG_MEMORY_HOTREMOVE */
#endif
/*
* Even when CONFIG_IA32_SUPPORT is not enabled it is
* useful to have the Linux/x86 domain registered to
* avoid an attempted module load when emulators call
* personality(PER_LINUX32). This saves several milliseconds
* on each such call.
*/
static struct exec_domain ia32_exec_domain;
static int __init
per_linux32_init(void)
{
ia32_exec_domain.name = "Linux/x86";
ia32_exec_domain.handler = NULL;
ia32_exec_domain.pers_low = PER_LINUX32;
ia32_exec_domain.pers_high = PER_LINUX32;
ia32_exec_domain.signal_map = default_exec_domain.signal_map;
ia32_exec_domain.signal_invmap = default_exec_domain.signal_invmap;
register_exec_domain(&ia32_exec_domain);
return 0;
}
__initcall(per_linux32_init);