Re: [PATCH v4 bpf-next 6/7] bpf: introduce bpf_prog_pack allocator
From: Alexei Starovoitov <hidden>
Date: 2022-01-20 04:14:37
Also in:
bpf, lkml
On Wed, Jan 19, 2022 at 03:06:19PM -0800, Song Liu wrote:
+/* + * BPF program pack allocator. + * + * Most BPF programs are pretty small. Allocating a hole page for each + * program is sometime a waste. Many small bpf program also adds pressure + * to instruction TLB. To solve this issue, we introduce a BPF program pack + * allocator. The prog_pack allocator uses HPAGE_PMD_SIZE page (2MB on x86) + * to host BPF programs. + */ +#define BPF_PROG_PACK_SIZE HPAGE_PMD_SIZE +#define BPF_PROG_MAX_PACK_PROG_SIZE HPAGE_PMD_SIZE
We have a synthetic test with 1M bpf instructions. How did it JIT? Are you saying we were lucky that every BPF insn was JITed to <2 bytes x86? Did I misread the 2MB limit?