| Message ID | 20230619100121.27534-1-puranjay12@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | bpf, arm64: use BPF prog pack allocator in BPF JIT | expand |
Hello: This series was applied to bpf/bpf-next.git (master) by Alexei Starovoitov <ast@kernel.org>: On Mon, 19 Jun 2023 10:01:18 +0000 you wrote: > BPF programs currently consume a page each on ARM64. For systems with many BPF > programs, this adds significant pressure to instruction TLB. High iTLB pressure > usually causes slow down for the whole system. > > Song Liu introduced the BPF prog pack allocator[1] to mitigate the above issue. > It packs multiple BPF programs into a single huge page. It is currently only > enabled for the x86_64 BPF JIT. > > [...] Here is the summary with links: - [bpf-next,v3,1/3] bpf: make bpf_prog_pack allocator portable https://git.kernel.org/bpf/bpf-next/c/9a44df2a4f2a - [bpf-next,v3,2/3] arm64: patching: Add aarch64_insn_copy() https://git.kernel.org/bpf/bpf-next/c/a7ed8ed92482 - [bpf-next,v3,3/3] bpf, arm64: use bpf_jit_binary_pack_alloc https://git.kernel.org/bpf/bpf-next/c/49703aa2adfa You are awesome, thank you!
BPF programs currently consume a page each on ARM64. For systems with many BPF programs, this adds significant pressure to instruction TLB. High iTLB pressure usually causes slow down for the whole system. Song Liu introduced the BPF prog pack allocator[1] to mitigate the above issue. It packs multiple BPF programs into a single huge page. It is currently only enabled for the x86_64 BPF JIT. This patch series enables the BPF prog pack allocator for the ARM64 BPF JIT. ==================================================== Performance Analysis of prog pack allocator on ARM64 ==================================================== To test the performance of the BPF prog pack allocator on ARM64, a stresser tool[2] was built. This tool loads 8 BPF programs on the system and triggers 5 of them in an infinite loop by doing system calls. The runner script starts 20 instances of the above which loads 8*20=160 BPF programs on the system, 5*20=100 of which are being constantly triggered. In the above environment we try to build Python-3.8.4 and try to find different iTLB metrics for the compilation done by gcc-12.2.0. The source code[3] is configured with the following command: ./configure --enable-optimizations --with-ensurepip=install Then the runner script is executed with the following command: ./run.sh "perf stat -e ITLB_WALK,L1I_TLB,INST_RETIRED,iTLB-load-misses -a make -j32" This builds Python while 160 BPF programs are loaded and 100 are being constantly triggered and measures iTLB related metrics. The output of the above command is discussed below before and after enabling the BPF prog pack allocator. The tests were run on qemu-system-aarch64 with 32 cpus, 4G memory, -machine virt, -cpu host, and -enable-kvm. Results ------- Before enabling prog pack allocator: ------------------------------------ Performance counter stats for 'system wide': 333278635 ITLB_WALK 6762692976558 L1I_TLB 25359571423901 INST_RETIRED 15824054789 iTLB-load-misses 189.029769053 seconds time elapsed After enabling prog pack allocator: ----------------------------------- Performance counter stats for 'system wide': 190333544 ITLB_WALK 6712712386528 L1I_TLB 25278233304411 INST_RETIRED 5716757866 iTLB-load-misses 185.392650561 seconds time elapsed Improvements in metrics ----------------------- Compilation time ---> 1.92% faster iTLB-load-misses/Sec (Less is better) ---> 63.16% decrease ITLB_WALK/1000 INST_RETIRED (Less is better) ---> 42.71% decrease ITLB_Walk/L1I_TLB (Less is better) ---> 42.47% decrease [1] https://lore.kernel.org/bpf/20220204185742.271030-1-song@kernel.org/ [2] https://github.com/puranjaymohan/BPF-Allocator-Bench [3] https://www.python.org/ftp/python/3.8.4/Python-3.8.4.tgz Chanes in V2 => V3: Changes only in 3rd patch 1. Set prog = orig_prog; in the failure path of bpf_jit_binary_pack_finalize() call. 2. Add comments explaining the usage of the offsets in the exception table. Changes in v1 => v2: 1. Make the naming consistent in the 3rd patch: ro_image and image ro_header and header ro_image_ptr and image_ptr 2. Use names dst/src in place of addr/opcode in second patch. 3. Add Acked-by: Song Liu <song@kernel.org> in 1st and 2nd patch. Puranjay Mohan (3): bpf: make bpf_prog_pack allocator portable arm64: patching: Add aarch64_insn_copy() bpf, arm64: use bpf_jit_binary_pack_alloc arch/arm64/include/asm/patching.h | 1 + arch/arm64/kernel/patching.c | 39 +++++++++ arch/arm64/net/bpf_jit_comp.c | 138 +++++++++++++++++++++++++----- kernel/bpf/core.c | 8 +- 4 files changed, 159 insertions(+), 27 deletions(-)