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change nxsched_islocked_global to nxsched_islocked_tcb #13716

Merged
merged 2 commits into from
Oct 5, 2024
Merged

change nxsched_islocked_global to nxsched_islocked_tcb #13716

merged 2 commits into from
Oct 5, 2024

Commits on Sep 29, 2024

  1. sched: change nxsched_islocked_global to nxsched_islocked_tcb 

    reason:
1 To improve efficiency, we mimic Linux's behavior where preemption disabling is only applicable to the current CPU and does not affect other CPUs.
2 In the future, we will implement "spinlock+sched_lock", and use it extensively. Under such circumstances, if preemption is still globally disabled, it will seriously impact the scheduling efficiency.
3 We have removed g_cpu_lockset and used irqcount in order to eliminate the dependency of schedlock on critical sections in the future, simplify the logic, and further enhance the performance of sched_lock.
4 We set lockcount to 1 in order to lock scheduling on all CPUs during startup, without the need to provide additional functions to disable scheduling on other CPUs.
5 Cpu1~n must wait for cpu0 to enter the idle state before enabling scheduling because it prevents CPUs1~n from competing with cpu0 for the memory manager mutex, which could cause the cpu0 idle task to enter a wait state and trigger an assert.

size nuttx
before:
   text    data     bss     dec     hex filename
 265396   51057   63646  380099   5ccc3 nuttx
after:
   text    data     bss     dec     hex filename
 265184   51057   63642  379883   5cbeb nuttx

size -216

Configuring NuttX and compile:
$ ./tools/configure.sh -l qemu-armv8a:nsh_smp
$ make
Running with qemu
$ qemu-system-aarch64 -cpu cortex-a53 -smp 4 -nographic \
   -machine virt,virtualization=on,gic-version=3 \
   -net none -chardev stdio,id=con,mux=on -serial chardev:con \
   -mon chardev=con,mode=readline -kernel ./nuttx

Signed-off-by: hujun5 <[email protected]>
    @hujun260
    hujun260 committed Sep 29, 2024
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  2. sched/sched: next pointer value is definitely not null 

    Signed-off-by: hujun5 <[email protected]>
    @hujun260
    hujun260 committed Sep 29, 2024
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