在 2024/3/28 2:17, Andrew Morton 写道:
On Fri, 26 Jan 2024 14:44:51 +0800 Huang Shijie <shi...@os.amperecomputing.com>
wrote:
During the kernel booting, the generic cpu_to_node() is called too early in
arm64, powerpc and riscv when CONFIG_NUMA is enabled.
There are at least four places in the common code where
the generic cpu_to_node() is called before it is initialized:
1.) early_trace_init() in kernel/trace/trace.c
2.) sched_init() in kernel/sched/core.c
3.) init_sched_fair_class() in kernel/sched/fair.c
4.) workqueue_init_early() in kernel/workqueue.c
In order to fix the bug, the patch introduces early_numa_node_init()
which is called after smp_prepare_boot_cpu() in start_kernel.
early_numa_node_init will initialize the "numa_node" as soon as
the early_cpu_to_node() is ready, before the cpu_to_node() is called
at the first time.
What are the userspace-visible runtime effects of this bug?
For this bug, I do not see too much performance impact in the userspace
applications.
It just pollutes the CPU caches in NUMA.
Thanks
Huang Shijie
