From 6c036527a630720063b67d9a65455e8caca2c8fa Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Thu, 7 Jul 2005 17:56:59 -0700 Subject: [PATCH] mostly_read data section Add a new section called ".data.read_mostly" for data items that are read frequently and rarely written to like cpumaps etc. If these maps are placed in the .data section then these frequenly read items may end up in cachelines with data is is frequently updated. In that case all processors in an SMP system must needlessly reload the cachelines again and again containing elements of those frequently used variables. The ability to share these cachelines will allow each cpu in an SMP system to keep local copies of those shared cachelines thereby optimizing performance. Signed-off-by: Alok N Kataria Signed-off-by: Shobhit Dayal Signed-off-by: Christoph Lameter Signed-off-by: Shai Fultheim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/cache.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux/cache.h') diff --git a/include/linux/cache.h b/include/linux/cache.h index 4d767b93738a..2b66a36d85f0 100644 --- a/include/linux/cache.h +++ b/include/linux/cache.h @@ -13,6 +13,12 @@ #define SMP_CACHE_BYTES L1_CACHE_BYTES #endif +#ifdef CONFIG_X86 +#define __read_mostly __attribute__((__section__(".data.read_mostly"))) +#else +#define __read_mostly +#endif + #ifndef ____cacheline_aligned #define ____cacheline_aligned __attribute__((__aligned__(SMP_CACHE_BYTES))) #endif -- cgit v1.2.3 From d369ddd2fc00fc3f46e9052d1017cbf407e3cdf7 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Sun, 10 Jul 2005 15:45:11 -0700 Subject: [SPARC64]: Add __read_mostly support. Signed-off-by: David S. Miller --- arch/sparc64/kernel/smp.c | 10 +++++----- arch/sparc64/kernel/time.c | 24 +++++++++--------------- arch/sparc64/kernel/vmlinux.lds.S | 2 ++ include/linux/cache.h | 2 +- 4 files changed, 17 insertions(+), 21 deletions(-) (limited to 'include/linux/cache.h') diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c index e5b9c7a27789..441fc2e52ce6 100644 --- a/arch/sparc64/kernel/smp.c +++ b/arch/sparc64/kernel/smp.c @@ -45,8 +45,8 @@ extern void calibrate_delay(void); /* Please don't make this stuff initdata!!! --DaveM */ static unsigned char boot_cpu_id; -cpumask_t cpu_online_map = CPU_MASK_NONE; -cpumask_t phys_cpu_present_map = CPU_MASK_NONE; +cpumask_t cpu_online_map = CPU_MASK_NONE __read_mostly; +cpumask_t phys_cpu_present_map = CPU_MASK_NONE __read_mostly; static cpumask_t smp_commenced_mask; static cpumask_t cpu_callout_map; @@ -155,7 +155,7 @@ void cpu_panic(void) panic("SMP bolixed\n"); } -static unsigned long current_tick_offset; +static unsigned long current_tick_offset __read_mostly; /* This tick register synchronization scheme is taken entirely from * the ia64 port, see arch/ia64/kernel/smpboot.c for details and credit. @@ -1193,8 +1193,8 @@ void smp_send_stop(void) { } -unsigned long __per_cpu_base; -unsigned long __per_cpu_shift; +unsigned long __per_cpu_base __read_mostly; +unsigned long __per_cpu_shift __read_mostly; EXPORT_SYMBOL(__per_cpu_base); EXPORT_SYMBOL(__per_cpu_shift); diff --git a/arch/sparc64/kernel/time.c b/arch/sparc64/kernel/time.c index b40db389f90b..362b9c26871b 100644 --- a/arch/sparc64/kernel/time.c +++ b/arch/sparc64/kernel/time.c @@ -73,7 +73,7 @@ static __initdata struct sparc64_tick_ops dummy_tick_ops = { .get_tick = dummy_get_tick, }; -struct sparc64_tick_ops *tick_ops = &dummy_tick_ops; +struct sparc64_tick_ops *tick_ops __read_mostly = &dummy_tick_ops; #define TICK_PRIV_BIT (1UL << 63) @@ -195,7 +195,7 @@ static unsigned long tick_add_tick(unsigned long adj, unsigned long offset) return new_tick; } -static struct sparc64_tick_ops tick_operations = { +static struct sparc64_tick_ops tick_operations __read_mostly = { .init_tick = tick_init_tick, .get_tick = tick_get_tick, .get_compare = tick_get_compare, @@ -276,7 +276,7 @@ static unsigned long stick_add_compare(unsigned long adj) return new_compare; } -static struct sparc64_tick_ops stick_operations = { +static struct sparc64_tick_ops stick_operations __read_mostly = { .init_tick = stick_init_tick, .get_tick = stick_get_tick, .get_compare = stick_get_compare, @@ -422,7 +422,7 @@ static unsigned long hbtick_add_compare(unsigned long adj) return val; } -static struct sparc64_tick_ops hbtick_operations = { +static struct sparc64_tick_ops hbtick_operations __read_mostly = { .init_tick = hbtick_init_tick, .get_tick = hbtick_get_tick, .get_compare = hbtick_get_compare, @@ -437,10 +437,9 @@ static struct sparc64_tick_ops hbtick_operations = { * NOTE: On SUN5 systems the ticker interrupt comes in using 2 * interrupts, one at level14 and one with softint bit 0. */ -unsigned long timer_tick_offset; -unsigned long timer_tick_compare; +unsigned long timer_tick_offset __read_mostly; -static unsigned long timer_ticks_per_nsec_quotient; +static unsigned long timer_ticks_per_nsec_quotient __read_mostly; #define TICK_SIZE (tick_nsec / 1000) @@ -464,7 +463,7 @@ static inline void timer_check_rtc(void) static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs * regs) { - unsigned long ticks, pstate; + unsigned long ticks, compare, pstate; write_seqlock(&xtime_lock); @@ -483,14 +482,14 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs * regs) : "=r" (pstate) : "i" (PSTATE_IE)); - timer_tick_compare = tick_ops->add_compare(timer_tick_offset); + compare = tick_ops->add_compare(timer_tick_offset); ticks = tick_ops->get_tick(); /* Restore PSTATE_IE. */ __asm__ __volatile__("wrpr %0, 0x0, %%pstate" : /* no outputs */ : "r" (pstate)); - } while (time_after_eq(ticks, timer_tick_compare)); + } while (time_after_eq(ticks, compare)); timer_check_rtc(); @@ -506,11 +505,6 @@ void timer_tick_interrupt(struct pt_regs *regs) do_timer(regs); - /* - * Only keep timer_tick_offset uptodate, but don't set TICK_CMPR. - */ - timer_tick_compare = tick_ops->get_compare() + timer_tick_offset; - timer_check_rtc(); write_sequnlock(&xtime_lock); diff --git a/arch/sparc64/kernel/vmlinux.lds.S b/arch/sparc64/kernel/vmlinux.lds.S index 382fd6798bb9..950423da8a6a 100644 --- a/arch/sparc64/kernel/vmlinux.lds.S +++ b/arch/sparc64/kernel/vmlinux.lds.S @@ -32,6 +32,8 @@ SECTIONS .data1 : { *(.data1) } . = ALIGN(64); .data.cacheline_aligned : { *(.data.cacheline_aligned) } + . = ALIGN(64); + .data.read_mostly : { *(.data.read_mostly) } _edata = .; PROVIDE (edata = .); .fixup : { *(.fixup) } diff --git a/include/linux/cache.h b/include/linux/cache.h index 2b66a36d85f0..f6b5a46c5f82 100644 --- a/include/linux/cache.h +++ b/include/linux/cache.h @@ -13,7 +13,7 @@ #define SMP_CACHE_BYTES L1_CACHE_BYTES #endif -#ifdef CONFIG_X86 +#if defined(CONFIG_X86) || defined(CONFIG_SPARC64) #define __read_mostly __attribute__((__section__(".data.read_mostly"))) #else #define __read_mostly -- cgit v1.2.3