rusty: Remove explicit padding

As of libbpf-rs 0.23.0 (which contains commit libbpf/libbpf-rs@9d9e979), libbpf-rs now generates rust structs that honor padding. We can therefore remove the custom padding in scx_rusty's struct pcpu_ctx. For example, here is the generated pub struct pcpu_ctx: pub struct pcpu_ctx { pub dom_rr_cur: u32, pub dom_id: u32, pub nr_node_doms: u32, pub node_doms: [u32; 64], pub __pad_268: [u8; 52], } And here is the matching struct in the BPF object file: struct pcpu_ctx { u32 dom_rr_cur; /* 0 4 */ u32 dom_id; /* 4 4 */ u32 nr_node_doms; /* 8 4 */ u32 node_doms[64]; /* 12 256 */ /* size: 320, cachelines: 5, members: 4 */ /* padding: 52 */ } __attribute__((__aligned__(64))); Signed-off-by: David Vernet <void@manifault.com>
takase1121 · Apr 12, 2024 · ffced1f · ffced1f
1 parent 5404303
commit ffced1f
Showing 1 changed file with 0 additions and 3 deletions.
diff --git a/scheds/rust/scx_rusty/src/bpf/main.bpf.c b/scheds/rust/scx_rusty/src/bpf/main.bpf.c
@@ -86,9 +86,6 @@ struct pcpu_ctx {
 	u32 dom_id;
 	u32 nr_node_doms;
 	u32 node_doms[MAX_DOMS];
-
-	/* libbpf-rs does not respect the alignment, so pad out the struct explicitly */
-	u8 _padding[CACHELINE_SIZE - ((3 + MAX_DOMS) * sizeof(u32) % CACHELINE_SIZE)];
 } __attribute__((aligned(CACHELINE_SIZE)));
 
 struct pcpu_ctx pcpu_ctx[MAX_CPUS];