On some architectures, secondary cores shares clock with primiary core and hence scale together. Hence secondary core lpj calibration is not necessary and can be skipped to save considerable time. This can speed up the secondary cpu boot and hotplug cpu online paths. Discussion thread: http://www.spinics.net/lists/arm-kernel/msg111124.html Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx> Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> Cc: Linus Walleij <linus.walleij@xxxxxxxxxxxxxx> --- arch/arm/Kconfig | 5 +++++ arch/arm/kernel/smp.c | 36 ++++++++++++++++++++++++++++-------- arch/arm/mach-omap2/Kconfig | 1 + 3 files changed, 34 insertions(+), 8 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 5cff165..8944639 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -823,6 +823,7 @@ config ARCH_U300 config ARCH_U8500 bool "ST-Ericsson U8500 Series" select CPU_V7 + select ARCH_HAS_COMMON_CORES_CLOCK select ARM_AMBA select GENERIC_CLOCKEVENTS select CLKDEV_LOOKUP @@ -1418,6 +1419,10 @@ config ARCH_SPARSEMEM_DEFAULT config ARCH_SELECT_MEMORY_MODEL def_bool ARCH_SPARSEMEM_ENABLE +config ARCH_HAS_COMMON_CORES_CLOCK + bool + depends on SMP + config HIGHMEM bool "High Memory Support (EXPERIMENTAL)" depends on MMU && EXPERIMENTAL diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 4539ebc..8e72b11 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -270,6 +270,20 @@ static void __cpuinit smp_store_cpu_info(unsigned int cpuid) } /* + * Skip the secondary calibration on architectures sharing clock + * with primary cpu. Archs can select ARCH_HAS_COMMON_CORES_CLOCK + * for this. + */ +static inline int skip_secondary_calibrate(void) +{ +#ifdef CONFIG_ARCH_HAS_COMMON_CORES_CLOCK + return true; +#else + return false; +#endif +} + +/* * This is the secondary CPU boot entry. We're using this CPUs * idle thread stack, but a set of temporary page tables. */ @@ -312,7 +326,8 @@ asmlinkage void __cpuinit secondary_start_kernel(void) */ percpu_timer_setup(); - calibrate_delay(); + if (!skip_secondary_calibrate()) + calibrate_delay(); smp_store_cpu_info(cpu); @@ -332,14 +347,19 @@ void __init smp_cpus_done(unsigned int max_cpus) int cpu; unsigned long bogosum = 0; - for_each_online_cpu(cpu) - bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy; + if (!skip_secondary_calibrate()) { + for_each_online_cpu(cpu) + bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy; - printk(KERN_INFO "SMP: Total of %d processors activated " - "(%lu.%02lu BogoMIPS).\n", - num_online_cpus(), - bogosum / (500000/HZ), - (bogosum / (5000/HZ)) % 100); + printk(KERN_INFO "SMP: Total of %d processors activated " + "(%lu.%02lu BogoMIPS).\n", + num_online_cpus(), + bogosum / (500000/HZ), + (bogosum / (5000/HZ)) % 100); + } else { + printk(KERN_INFO "SMP: Total of %d processors activated.\n", + num_online_cpus()); + } } void __init smp_prepare_boot_cpu(void) diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig index 1a2cf62..e6ad15d 100644 --- a/arch/arm/mach-omap2/Kconfig +++ b/arch/arm/mach-omap2/Kconfig @@ -43,6 +43,7 @@ config ARCH_OMAP4 default y depends on ARCH_OMAP2PLUS select CPU_V7 + select ARCH_HAS_COMMON_CORES_CLOCK select ARM_GIC select PL310_ERRATA_588369 select ARM_ERRATA_720789 -- 1.6.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
