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-rw-r--r--init/Kconfig77
-rw-r--r--init/main.c46
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);
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-24 07:51:10 +0000