Use module_alloc_huge for bpf_prog_pack so that BPF programs sit on PMD_SIZE pages. This benefits system performance by reducing iTLB miss rate. Benchmark of a real web service workload shows this change gives another ~0.2% performance boost on top of PAGE_SIZE bpf_prog_pack (which improve system throughput by ~0.5%). Also, remove set_vm_flush_reset_perms() from alloc_new_pack() and use set_memory_[nx|rw] in bpf_prog_pack_free(). This is because VM_FLUSH_RESET_PERMS does not work with huge pages yet. [1] [1] https://lore.kernel.org/bpf/aeeeaf0b7ec63fdba55d4834d2f524d8bf05b71b.camel@xxxxxxxxx/ Suggested-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx> Signed-off-by: Song Liu <song@xxxxxxxxxx> --- kernel/bpf/core.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 805c2ad5c793..d1f32ac354d3 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -860,7 +860,7 @@ static size_t select_bpf_prog_pack_size(void) void *ptr; size = BPF_HPAGE_SIZE * num_online_nodes(); - ptr = module_alloc(size); + ptr = module_alloc_huge(size); /* Test whether we can get huge pages. If not just use PAGE_SIZE * packs. @@ -884,7 +884,7 @@ static struct bpf_prog_pack *alloc_new_pack(bpf_jit_fill_hole_t bpf_fill_ill_ins GFP_KERNEL); if (!pack) return NULL; - pack->ptr = module_alloc(bpf_prog_pack_size); + pack->ptr = module_alloc_huge(bpf_prog_pack_size); if (!pack->ptr) { kfree(pack); return NULL; @@ -893,7 +893,6 @@ static struct bpf_prog_pack *alloc_new_pack(bpf_jit_fill_hole_t bpf_fill_ill_ins bitmap_zero(pack->bitmap, bpf_prog_pack_size / BPF_PROG_CHUNK_SIZE); list_add_tail(&pack->list, &pack_list); - set_vm_flush_reset_perms(pack->ptr); set_memory_ro((unsigned long)pack->ptr, bpf_prog_pack_size / PAGE_SIZE); set_memory_x((unsigned long)pack->ptr, bpf_prog_pack_size / PAGE_SIZE); return pack; @@ -912,10 +911,9 @@ static void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insn if (size > bpf_prog_pack_size) { size = round_up(size, PAGE_SIZE); - ptr = module_alloc(size); + ptr = module_alloc_huge(size); if (ptr) { bpf_fill_ill_insns(ptr, size); - set_vm_flush_reset_perms(ptr); set_memory_ro((unsigned long)ptr, size / PAGE_SIZE); set_memory_x((unsigned long)ptr, size / PAGE_SIZE); } @@ -952,6 +950,8 @@ static void bpf_prog_pack_free(struct bpf_binary_header *hdr) mutex_lock(&pack_mutex); if (hdr->size > bpf_prog_pack_size) { + set_memory_nx((unsigned long)hdr, hdr->size / PAGE_SIZE); + set_memory_rw((unsigned long)hdr, hdr->size / PAGE_SIZE); module_memfree(hdr); goto out; } @@ -978,6 +978,8 @@ static void bpf_prog_pack_free(struct bpf_binary_header *hdr) if (bitmap_find_next_zero_area(pack->bitmap, bpf_prog_chunk_count(), 0, bpf_prog_chunk_count(), 0) == 0) { list_del(&pack->list); + set_memory_nx((unsigned long)pack->ptr, bpf_prog_pack_size / PAGE_SIZE); + set_memory_rw((unsigned long)pack->ptr, bpf_prog_pack_size / PAGE_SIZE); module_memfree(pack->ptr); kfree(pack); } -- 2.30.2
