diff options
| author | Stafford Horne <shorne@gmail.com> | 2017-06-24 07:09:59 +0900 |
|---|---|---|
| committer | Stafford Horne <shorne@gmail.com> | 2017-11-03 14:01:14 +0900 |
| commit | c056718464512da06d7f65a27d5e4f1707b24c80 (patch) | |
| tree | 3b3b3076d876428ae8b81826f7171f22e84009a5 /arch/openrisc/kernel/smp.c | |
| parent | b441aab7aa0e15955c432736b08a218a6a4c77f0 (diff) | |
openrisc: sleep instead of spin on secondary wait
Currently we do a spin on secondary cpus when waiting to boot. This
theoretically causes issues with power consumption and does cause issues
with qemu cycle burning (it starves cpu 0 from actually being able to
boot.)
This change puts each secondary cpu to sleep if they have a power
management unit, then signals them to wake via IPI when its time to boot.
If the cpus have no power management unit they will loop as before.
Note: The wakeup IPI requires a special interrupt handler as on secondary
cpu's the interrupt infrastructure is not yet established. This
interrupt handler is set and reset by updating SPR_EVBAR.
Signed-off-by: Stafford Horne <shorne@gmail.com>
Diffstat (limited to 'arch/openrisc/kernel/smp.c')
| -rw-r--r-- | arch/openrisc/kernel/smp.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/openrisc/kernel/smp.c b/arch/openrisc/kernel/smp.c index 154c94a0cfbc..685b4934fa39 100644 --- a/arch/openrisc/kernel/smp.c +++ b/arch/openrisc/kernel/smp.c @@ -26,6 +26,7 @@ unsigned long secondary_release = -1; struct thread_info *secondary_thread_info; enum ipi_msg_type { + IPI_WAKEUP, IPI_RESCHEDULE, IPI_CALL_FUNC, IPI_CALL_FUNC_SINGLE, @@ -42,6 +43,7 @@ static void boot_secondary(unsigned int cpu, struct task_struct *idle) spin_lock(&boot_lock); secondary_release = cpu; + smp_cross_call(cpumask_of(cpu), IPI_WAKEUP); /* * now the secondary core is starting up let it run its @@ -140,6 +142,9 @@ void handle_IPI(unsigned int ipi_msg) unsigned int cpu = smp_processor_id(); switch (ipi_msg) { + case IPI_WAKEUP: + break; + case IPI_RESCHEDULE: scheduler_ipi(); break; |