The uevent handling in udevd is not cpu hungry.
So, let's increase the default number of workers per cpu.
This decrease the number of queued uevents.
Without this commit (children_max is 16 on my laptop)
```
$ journalctl -b -u systemd-udevd.service | grep reached | wc -l
1544
```
With this commit (children_max is 30 on my laptop)
```
$ journalctl -b -u systemd-udevd.service | grep reached | wc -l
7
```
arg_children_max = 8;
if (sched_getaffinity(0, sizeof(cpu_set), &cpu_set) == 0)
- arg_children_max += CPU_COUNT(&cpu_set) * 2;
+ arg_children_max += CPU_COUNT(&cpu_set) * 8;
mem_limit = physical_memory() / (128LU*1024*1024);
arg_children_max = MAX(10U, MIN(arg_children_max, mem_limit));