diff options
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 77 | ||||
| -rw-r--r-- | init/main.c | 46 |
2 files changed, 77 insertions, 46 deletions
diff --git a/init/Kconfig b/init/Kconfig index 8f97a740771..66f67afad4f 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -28,10 +28,6 @@ config BUILDTIME_EXTABLE_SORT menu "General setup" -config EXPERIMENTAL - bool - default y - config BROKEN bool @@ -583,13 +579,16 @@ config RCU_FAST_NO_HZ depends on NO_HZ_COMMON && SMP default n help - This option causes RCU to attempt to accelerate grace periods in - order to allow CPUs to enter dynticks-idle state more quickly. - On the other hand, this option increases the overhead of the - dynticks-idle checking, thus degrading scheduling latency. + This option permits CPUs to enter dynticks-idle state even if + they have RCU callbacks queued, and prevents RCU from waking + these CPUs up more than roughly once every four jiffies (by + default, you can adjust this using the rcutree.rcu_idle_gp_delay + parameter), thus improving energy efficiency. On the other + hand, this option increases the duration of RCU grace periods, + for example, slowing down synchronize_rcu(). - Say Y if energy efficiency is critically important, and you don't - care about real-time response. + Say Y if energy efficiency is critically important, and you + don't care about increased grace-period durations. Say N if you are unsure. @@ -656,7 +655,7 @@ config RCU_BOOST_DELAY Accept the default if unsure. config RCU_NOCB_CPU - bool "Offload RCU callback processing from boot-selected CPUs" + bool "Offload RCU callback processing from boot-selected CPUs (EXPERIMENTAL" depends on TREE_RCU || TREE_PREEMPT_RCU default n help @@ -667,16 +666,56 @@ config RCU_NOCB_CPU This option offloads callback invocation from the set of CPUs specified at boot time by the rcu_nocbs parameter. - For each such CPU, a kthread ("rcuoN") will be created to - invoke callbacks, where the "N" is the CPU being offloaded. - Nothing prevents this kthread from running on the specified - CPUs, but (1) the kthreads may be preempted between each - callback, and (2) affinity or cgroups can be used to force - the kthreads to run on whatever set of CPUs is desired. - - Say Y here if you want reduced OS jitter on selected CPUs. + For each such CPU, a kthread ("rcuox/N") will be created to + invoke callbacks, where the "N" is the CPU being offloaded, + and where the "x" is "b" for RCU-bh, "p" for RCU-preempt, and + "s" for RCU-sched. Nothing prevents this kthread from running + on the specified CPUs, but (1) the kthreads may be preempted + between each callback, and (2) affinity or cgroups can be used + to force the kthreads to run on whatever set of CPUs is desired. + + Say Y here if you want to help to debug reduced OS jitter. Say N here if you are unsure. +choice + prompt "Build-forced no-CBs CPUs" + default RCU_NOCB_CPU_NONE + help + This option allows no-CBs CPUs to be specified at build time. + Additional no-CBs CPUs may be specified by the rcu_nocbs= + boot parameter. + +config RCU_NOCB_CPU_NONE + bool "No build_forced no-CBs CPUs" + depends on RCU_NOCB_CPU + help + This option does not force any of the CPUs to be no-CBs CPUs. + Only CPUs designated by the rcu_nocbs= boot parameter will be + no-CBs CPUs. + +config RCU_NOCB_CPU_ZERO + bool "CPU 0 is a build_forced no-CBs CPU" + depends on RCU_NOCB_CPU + help + This option forces CPU 0 to be a no-CBs CPU. Additional CPUs + may be designated as no-CBs CPUs using the rcu_nocbs= boot + parameter will be no-CBs CPUs. + + Select this if CPU 0 needs to be a no-CBs CPU for real-time + or energy-efficiency reasons. + +config RCU_NOCB_CPU_ALL + bool "All CPUs are build_forced no-CBs CPUs" + depends on RCU_NOCB_CPU + help + This option forces all CPUs to be no-CBs CPUs. The rcu_nocbs= + boot parameter will be ignored. + + Select this if all CPUs need to be no-CBs CPUs for real-time + or energy-efficiency reasons. + +endchoice + endmenu # "RCU Subsystem" config IKCONFIG diff --git a/init/main.c b/init/main.c index 2acb5bbde99..1952bf2f687 100644 --- a/init/main.c +++ b/init/main.c @@ -9,6 +9,8 @@ * Simplified starting of init: Michael A. Griffith <grif@acm.org> */ +#define DEBUG /* Enable initcall_debug */ + #include <linux/types.h> #include <linux/module.h> #include <linux/proc_fs.h> @@ -174,8 +176,8 @@ static int __init obsolete_checksetup(char *line) if (line[n] == '\0' || line[n] == '=') had_early_param = 1; } else if (!p->setup_func) { - printk(KERN_WARNING "Parameter %s is obsolete," - " ignored\n", p->str); + pr_warn("Parameter %s is obsolete, ignored\n", + p->str); return 1; } else if (p->setup_func(line + n)) return 1; @@ -384,7 +386,7 @@ static noinline void __init_refok rest_init(void) init_idle_bootup_task(current); schedule_preempt_disabled(); /* Call into cpu_idle with preempt disabled */ - cpu_idle(); + cpu_startup_entry(CPUHP_ONLINE); } /* Check for early params. */ @@ -398,8 +400,7 @@ static int __init do_early_param(char *param, char *val, const char *unused) strcmp(p->str, "earlycon") == 0) ) { if (p->setup_func(val) != 0) - printk(KERN_WARNING - "Malformed early option '%s'\n", param); + pr_warn("Malformed early option '%s'\n", param); } } /* We accept everything at this stage. */ @@ -497,7 +498,7 @@ asmlinkage void __init start_kernel(void) tick_init(); boot_cpu_init(); page_address_init(); - printk(KERN_NOTICE "%s", linux_banner); + pr_notice("%s", linux_banner); setup_arch(&command_line); mm_init_owner(&init_mm, &init_task); mm_init_cpumask(&init_mm); @@ -509,7 +510,7 @@ asmlinkage void __init start_kernel(void) build_all_zonelists(NULL, NULL); page_alloc_init(); - printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line); + pr_notice("Kernel command line: %s\n", boot_command_line); parse_early_param(); parse_args("Booting kernel", static_command_line, __start___param, __stop___param - __start___param, @@ -539,11 +540,8 @@ asmlinkage void __init start_kernel(void) * fragile until we cpu_idle() for the first time. */ preempt_disable(); - if (!irqs_disabled()) { - printk(KERN_WARNING "start_kernel(): bug: interrupts were " - "enabled *very* early, fixing it\n"); + if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n")) local_irq_disable(); - } idr_init_cache(); perf_event_init(); rcu_init(); @@ -559,9 +557,7 @@ asmlinkage void __init start_kernel(void) time_init(); profile_init(); call_function_init(); - if (!irqs_disabled()) - printk(KERN_CRIT "start_kernel(): bug: interrupts were " - "enabled early\n"); + WARN(!irqs_disabled(), "Interrupts were enabled early\n"); early_boot_irqs_disabled = false; local_irq_enable(); @@ -588,8 +584,7 @@ asmlinkage void __init start_kernel(void) #ifdef CONFIG_BLK_DEV_INITRD if (initrd_start && !initrd_below_start_ok && page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) { - printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - " - "disabling it.\n", + pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n", page_to_pfn(virt_to_page((void *)initrd_start)), min_low_pfn); initrd_start = 0; @@ -668,14 +663,14 @@ static int __init_or_module do_one_initcall_debug(initcall_t fn) unsigned long long duration; int ret; - printk(KERN_DEBUG "calling %pF @ %i\n", fn, task_pid_nr(current)); + pr_debug("calling %pF @ %i\n", fn, task_pid_nr(current)); calltime = ktime_get(); ret = fn(); rettime = ktime_get(); delta = ktime_sub(rettime, calltime); duration = (unsigned long long) ktime_to_ns(delta) >> 10; - printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n", fn, - ret, duration); + pr_debug("initcall %pF returned %d after %lld usecs\n", + fn, ret, duration); return ret; } @@ -703,9 +698,7 @@ int __init_or_module do_one_initcall(initcall_t fn) strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf)); local_irq_enable(); } - if (msgbuf[0]) { - printk("initcall %pF returned with %s\n", fn, msgbuf); - } + WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf); return ret; } @@ -833,8 +826,7 @@ static int __ref kernel_init(void *unused) if (ramdisk_execute_command) { if (!run_init_process(ramdisk_execute_command)) return 0; - printk(KERN_WARNING "Failed to execute %s\n", - ramdisk_execute_command); + pr_err("Failed to execute %s\n", ramdisk_execute_command); } /* @@ -846,8 +838,8 @@ static int __ref kernel_init(void *unused) if (execute_command) { if (!run_init_process(execute_command)) return 0; - printk(KERN_WARNING "Failed to execute %s. Attempting " - "defaults...\n", execute_command); + pr_err("Failed to execute %s. Attempting defaults...\n", + execute_command); } if (!run_init_process("/sbin/init") || !run_init_process("/etc/init") || @@ -892,7 +884,7 @@ static noinline void __init kernel_init_freeable(void) /* Open the /dev/console on the rootfs, this should never fail */ if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) - printk(KERN_WARNING "Warning: unable to open an initial console.\n"); + pr_err("Warning: unable to open an initial console.\n"); (void) sys_dup(0); (void) sys_dup(0); |