On 2024/10/17 00:57, Alexei Starovoitov wrote:
On Tue, Oct 15, 2024 at 7:42 PM Tianchen Ding <dtcccc@xxxxxxxxxxxxxxxxx> wrote:
Save the searching time during bpf_scx_init.
Signed-off-by: Tianchen Ding <dtcccc@xxxxxxxxxxxxxxxxx>
---
kernel/sched/ext.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 609b9fb00d6f..1d11a96eefb8 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -5343,7 +5343,7 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link)
extern struct btf *btf_vmlinux;
static const struct btf_type *task_struct_type;
-static u32 task_struct_type_id;
+BTF_ID_LIST_SINGLE(task_struct_btf_ids, struct, task_struct);
static bool set_arg_maybe_null(const char *op, int arg_n, int off, int size,
enum bpf_access_type type,
@@ -5395,7 +5395,7 @@ static bool set_arg_maybe_null(const char *op, int arg_n, int off, int size,
*/
info->reg_type = PTR_MAYBE_NULL | PTR_TO_BTF_ID | PTR_TRUSTED;
info->btf = btf_vmlinux;
- info->btf_id = task_struct_type_id;
+ info->btf_id = task_struct_btf_ids[0];
return true;
}
@@ -5547,13 +5547,7 @@ static void bpf_scx_unreg(void *kdata, struct bpf_link *link)
static int bpf_scx_init(struct btf *btf)
{
- s32 type_id;
-
- type_id = btf_find_by_name_kind(btf, "task_struct", BTF_KIND_STRUCT);
- if (type_id < 0)
- return -EINVAL;
- task_struct_type = btf_type_by_id(btf, type_id);
- task_struct_type_id = type_id;
+ task_struct_type = btf_type_by_id(btf, task_struct_btf_ids[0]);
Good optimization, but it's also unnecessary.
btf_id is already in btf_tracing_ids[BTF_TRACING_TYPE_TASK].
Get it. Thanks!
BTW, do you think we should add a zero check for
btf_tracing_ids[BTF_TRACING_TYPE_TASK] here?
task_struct should always be valid. If something wrong, resolve_btfids will also
throw a warning. I'm not sure whether to add a sanity check here.
