Re: [PATCH v6 0/5] powerpc/bpf: use BPF prog pack allocator

[Daniel Borkmann <daniel@iogearbox.net>]

On 10/12/23 10:03 PM, Hari Bathini wrote:
> 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.
> 
> Both bpf_arch_text_copy() & bpf_arch_text_invalidate() functions,
> needed for this support depend on instruction patching in text area.
> Currently, patch_instruction() supports patching only one instruction
> at a time. The first patch introduces patch_instructions() function
> to enable patching more than one instruction at a time. This helps in
> avoiding performance degradation while JITing bpf programs.
> 
> Patches 2 & 3 implement the above mentioned arch specific functions
> using patch_instructions(). Patch 4 fixes a misnomer in bpf JITing
> code. The last patch enables the use of BPF prog pack allocator on
> powerpc and also, ensures cleanup is handled gracefully.
> 
> [1] https://lore.kernel.org/bpf/20220204185742.271030-1-song@kernel.org/
> 
> Changes in v6:
> * No changes in patches 2-5/5 except addition of Acked-by tags from Song.
> * Skipped merging code path of patch_instruction() & patch_instructions()
>    to avoid performance overhead observed on ppc32 with that.

I presume this will be routed via Michael?

Thanks,
Daniel