[RFC PATCH 0/3] enable bpf_prog_pack allocator for powerpc

[Hari Bathini]

Hi Christophe,

On 11/11/22 4:55 pm, Christophe Leroy wrote:
> Le 10/11/2022 à 19:43, Hari Bathini a écrit :
>> Most BPF programs are small, but they consume a page each. For systems
>> with busy traffic and many BPF programs, this may also add significant
>> pressure on instruction TLB. High iTLB pressure usually slows down the
>> whole system causing visible performance degradation for production
>> workloads.
>>
>> bpf_prog_pack, a customized allocator that packs multiple bpf programs
>> into preallocated memory chunks, was proposed [1] to address it. This
>> series extends this support on powerpc.
>>
>> Patches 1 & 2 add the arch specific functions needed to support this
>> feature. Patch 3 enables the support for powerpc. The last patch
>> ensures cleanup is handled racefully.
>>

>> Tested the changes successfully on a PowerVM. patch_instruction(),
>> needed for bpf_arch_text_copy(), is failing for ppc32. Debugging it.
>> Posting the patches in the meanwhile for feedback on these changes.
> 
> I did a quick test on ppc32, I don't get such a problem, only something
> wrong in the dump print as traps intructions only are dumped, but
> tcpdump works as expected:

Thanks for the quick test. Could you please share the config you used.
I am probably missing a few knobs in my conifg...

Thanks
Hari