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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2011-01-05 12:48:08 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com> | 2011-01-05 12:47:30 +0100 |
| commit | f230886b0b0f0ce604395481bea05f3c0ad8fc9e (patch) | |
| tree | 939fd68ab2ed93420dcb0b439245b553763c2284 /arch/s390 | |
| parent | 09a8e7adcf960bd6a7204f3f3b377a89ce22efbf (diff) | |
| download | linux-f230886b0b0f0ce604395481bea05f3c0ad8fc9e.tar.gz linux-f230886b0b0f0ce604395481bea05f3c0ad8fc9e.tar.bz2 linux-f230886b0b0f0ce604395481bea05f3c0ad8fc9e.zip | |
[S390] smp: delay idle task creation
Delay idle task creation until a cpu gets set online instead of
creating them for all possible cpus at system startup.
For one cpu system this should safe more than 1 MB.
On my debug system with lots of debug stuff enabled this saves 2 MB.
Same as on x86.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/kernel/smp.c | 41 |
1 files changed, 26 insertions, 15 deletions
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index a9702df22f3a..8e84b5af49ba 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -23,6 +23,7 @@ #define KMSG_COMPONENT "cpu" #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt +#include <linux/workqueue.h> #include <linux/module.h> #include <linux/init.h> #include <linux/mm.h> @@ -477,18 +478,20 @@ int __cpuinit start_secondary(void *cpuvoid) return 0; } -static void __init smp_create_idle(unsigned int cpu) +struct create_idle { + struct work_struct work; + struct task_struct *idle; + struct completion done; + int cpu; +}; + +static void __cpuinit smp_fork_idle(struct work_struct *work) { - struct task_struct *p; + struct create_idle *c_idle; - /* - * don't care about the psw and regs settings since we'll never - * reschedule the forked task. - */ - p = fork_idle(cpu); - if (IS_ERR(p)) - panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p)); - current_set[cpu] = p; + c_idle = container_of(work, struct create_idle, work); + c_idle->idle = fork_idle(c_idle->cpu); + complete(&c_idle->done); } static int __cpuinit smp_alloc_lowcore(int cpu) @@ -552,6 +555,7 @@ static void smp_free_lowcore(int cpu) int __cpuinit __cpu_up(unsigned int cpu) { struct _lowcore *cpu_lowcore; + struct create_idle c_idle; struct task_struct *idle; struct stack_frame *sf; u32 lowcore; @@ -559,6 +563,18 @@ int __cpuinit __cpu_up(unsigned int cpu) if (smp_cpu_state[cpu] != CPU_STATE_CONFIGURED) return -EIO; + idle = current_set[cpu]; + if (!idle) { + c_idle.done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done); + INIT_WORK_ONSTACK(&c_idle.work, smp_fork_idle); + c_idle.cpu = cpu; + schedule_work(&c_idle.work); + wait_for_completion(&c_idle.done); + if (IS_ERR(c_idle.idle)) + return PTR_ERR(c_idle.idle); + idle = c_idle.idle; + current_set[cpu] = c_idle.idle; + } if (smp_alloc_lowcore(cpu)) return -ENOMEM; do { @@ -573,7 +589,6 @@ int __cpuinit __cpu_up(unsigned int cpu) while (sigp_p(lowcore, cpu, sigp_set_prefix) == sigp_busy) udelay(10); - idle = current_set[cpu]; cpu_lowcore = lowcore_ptr[cpu]; cpu_lowcore->kernel_stack = (unsigned long) task_stack_page(idle) + THREAD_SIZE; @@ -685,7 +700,6 @@ void __init smp_prepare_cpus(unsigned int max_cpus) #endif unsigned long async_stack, panic_stack; struct _lowcore *lowcore; - unsigned int cpu; smp_detect_cpus(); @@ -720,9 +734,6 @@ void __init smp_prepare_cpus(unsigned int max_cpus) if (vdso_alloc_per_cpu(smp_processor_id(), &S390_lowcore)) BUG(); #endif - for_each_possible_cpu(cpu) - if (cpu != smp_processor_id()) - smp_create_idle(cpu); } void __init smp_prepare_boot_cpu(void) |