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

Hari Bathini hbathini at linux.ibm.com
Tue Oct 17 17:26:09 AEDT 2023

On 16/10/23 5:37 pm, Daniel Borkmann wrote:
> 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?

Yes, Daniel. This can go via linuxppc tree.


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