aboutsummaryrefslogtreecommitdiff
path: root/arch/s390/kernel
diff options
context:
space:
mode:
authorHeiko Carstens <heiko.carstens@de.ibm.com>2011-01-05 12:48:08 +0100
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2011-01-05 12:47:30 +0100
commitf230886b0b0f0ce604395481bea05f3c0ad8fc9e (patch)
tree939fd68ab2ed93420dcb0b439245b553763c2284 /arch/s390/kernel
parent09a8e7adcf960bd6a7204f3f3b377a89ce22efbf (diff)
downloadlinux-linaro-stable-f230886b0b0f0ce604395481bea05f3c0ad8fc9e.tar.gz
[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/kernel')
-rw-r--r--arch/s390/kernel/smp.c41
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)