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@xxxxxxxxx> diff -uprN -X linux-2.6.26-rc1/Documentation/dontdiff linux-2.6.26-rc1/arch/ia64/ia32/ia32_support.c linux-2.6.26-fix/arch/ia64/ia32/ia32_support.c --- linux-2.6.26-rc1/arch/ia64/ia32/ia32_support.c 2008-05-04 02:59:44.000000000 +0800 +++ linux-2.6.26-fix/arch/ia64/ia32/ia32_support.c 2008-05-15 00:48:46.000000000 +0800 @@ -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; diff -uprN -X linux-2.6.26-rc1/Documentation/dontdiff linux-2.6.26-rc1/arch/ia64/mm/init.c linux-2.6.26-fix/arch/ia64/mm/init.c --- linux-2.6.26-rc1/arch/ia64/mm/init.c 2008-05-04 02:59:44.000000000 +0800 +++ linux-2.6.26-fix/arch/ia64/mm/init.c 2008-05-15 00:49:23.000000000 +0800 @@ -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); Thanks Xiaolan -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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