> On Jan 19, 2022, at 8:14 PM, Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote: > > 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? The logic is, if the program is bigger than 2MB, we fall back to use module_alloc(). This limitation simplifies the bpf_prog_pack allocator. Thanks, Song
