答复: [RFC 1/2] eal: add llc aware functions

[Feifei Wang <wangfeifei@hygon.cn>]

Hi,

> -----邮件原件-----
> 发件人: Wathsala Wathawana Vithanage <wathsala.vithanage@arm.com>
> 发送时间: 2024年8月28日 4:56
> 收件人: Vipin Varghese <vipin.varghese@amd.com>; ferruh.yigit@amd.com;
> dev@dpdk.org
> 抄送: nd <nd@arm.com>; nd <nd@arm.com>
> 主题: RE: [RFC 1/2] eal: add llc aware functions
> 
> > -unsigned int rte_get_next_lcore(unsigned int i, int skip_main, int wrap)
> > +#define LCORE_GET_LLC   \
> > +		"ls -d /sys/bus/cpu/devices/cpu%u/cache/index[0-9] | sort  -r
> > | grep -m1 index[0-9] | awk -F '[x]' '{print $2}' "
> >
> 
> This won't work for some SOCs.
> How to ensure the index you got is for an LLC? Some SOCs may only show
> upper-level caches here, therefore cannot be use blindly without knowing the
> SOC.
> Also, unacceptable to execute a shell script, consider implementing in C.

Maybe：
For arm, maybe we can load MPIDR_EL1 register to achieve cpu cluster topology.
MPIDR_EL1 register bit meaning:
[23:16]	AFF3	 (Level 3 affinity)
[15:8]	AFF2	 (Level 2 affinity)
[7:0]	AFF1	(Level 1 affinity)
[7:0]	AFF0	(Level 0 affinity)

For x86, we can use apic_id:
Apic_id includes cluster id, die id, smt id and core id.
 
This bypass execute a shell script, and for arm and x86, we set different path to implement this.

Best Regards
Feifei
> --wathsala
>