For benchmarking or debugging purpose, we usually want to control SMT
via boot parameter and sysfs knobs. So add HOTPLUG_SMT implementation.
1. Boot parameters:
nosmt: Disable SMT, can be enabled via sysfs knobs.
nosmt=force: Disable SMT, cannot be enabled via sysfs knobs.
2. Runtime sysfs controls:
Write "on", "off", "forceoff" or the number of SMT threads (1, 2, ...)
to /sys/devices/system/cpu/smt/control.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
In order to achieve more reasonable load balancing behavior, add
SCHED_MC (Multi-core scheduler) support.
The LLC distribution of LoongArch now is consistent with NUMA node,
the balancing domain of SCHED_MC can effectively reduce the situation
where processes are awakened to smt_sibling.
Co-developed-by: Hongliang Wang <wanghongliang@loongson.cn>
Signed-off-by: Hongliang Wang <wanghongliang@loongson.cn>
Signed-off-by: Tianyang Zhang <zhangtianyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
When CONFIG_RANDOM_KMALLOC_CACHES or other randomization infrastructrue
enabled, the idle_task's stack may different between the booting kernel
and target kernel. So when resuming from hibernation, an ACTION_BOOT_CPU
IPI wakeup the idle instruction in arch_cpu_idle_dead() and jump to the
interrupt handler. But since the stack pointer is changed, the interrupt
handler cannot restore correct context.
So rename the current arch_cpu_idle_dead() to idle_play_dead(), make it
as the default version of play_dead(), and the new arch_cpu_idle_dead()
call play_dead() directly. For hibernation, implement an arch-specific
hibernate_resume_nonboot_cpu_disable() to use the polling version (idle
instruction is replace by nop, and irq is disabled) of play_dead(), i.e.
poll_play_dead(), to avoid IPI handler corrupting the idle_task's stack
when resuming from hibernation.
This solution is a little similar to commit 406f992e4a372dafbe3c ("x86 /
hibernate: Use hlt_play_dead() when resuming from hibernation").
Cc: stable@vger.kernel.org
Tested-by: Erpeng Xu <xuerpeng@uniontech.com>
Tested-by: Yuli Wang <wangyuli@uniontech.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
Performance improvement for reading /proc/interrupts on LoongArch.
On a system with n CPUs and m interrupts, there will be n*m decimal
values yielded via seq_printf(.."%10u "..) which is less efficient than
seq_put_decimal_ull_width(), stress reading /proc/interrupts indicates
~30% performance improvement with this patch (and its friends).
Signed-off-by: David Wang <00107082@163.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: michael <michael5hzg@gmail.com>
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
maoxiaochuan