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Commit 839052d2 authored by Huang, Xiaolan's avatar Huang, Xiaolan Committed by Tony Luck
Browse files

[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: default avatarXiaolan Huang <xiaolan.huang@intel.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 3fb2c74e

arch/ia64/ia32/ia32_support.c

+0 −10
Original line number Diff line number Diff line
@@ -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;

arch/ia64/mm/init.c

+25 −0
Original line number Diff line number Diff line
@@ -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);