# Re: \[PATCH v3\] sched/numa: add per-process numa\_balancing

- From: Gang Li \<hidden\>
- Date: 2021-12-13 06:51:16 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2021/12/219843
- Thread: https://ratatoskr.run/linux-api/2021/12/219366/t.md

```text
Hi,
Any comments plz ;)

On 2021/12/6 10:45, Gang Li wrote:
> This patch add a new api PR_NUMA_BALANCING in prctl.
>
> A large number of page faults will cause performance loss when numa
> balancing is performing. Thus those processes which care about worst-case
> performance need numa balancing disabled. Others, on the contrary, allow a
> temporary performance loss in exchange for higher average performance, so
> enable numa balancing is better for them.
>
> Numa balancing can only be controlled globally by
> /proc/sys/kernel/numa_balancing. Due to the above case, we want to
> disable/enable numa_balancing per-process instead.
>
> Add numa_balancing under mm_struct. Then use it in task_tick_fair.
>
> Set per-process numa balancing:
> 	prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_DISABLE); //disable
> 	prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_ENABLE);  //enable
> 	prctl(PR_NUMA_BALANCING, PR_SET_NUMAB_DEFAULT); //follow global
> Get numa_balancing state:
> 	prctl(PR_NUMA_BALANCING, PR_GET_NUMAB, &ret);
> 	cat /proc/<pid>/status | grep NumaB_enabled
>
> Cc: <redacted>
> Signed-off-by: Gang Li <redacted>


```