| Message ID | 20241016024100.7409-1-dtcccc@linux.alibaba.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | BPF |
| Headers | show |
| Series | sched_ext: Use BTF_ID to resolve task_struct | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Tue, Oct 15, 2024 at 7:42 PM Tianchen Ding <dtcccc@linux.alibaba.com> wrote: > > Save the searching time during bpf_scx_init. > > Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com> > --- > 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].
On 2024/10/17 00:57, Alexei Starovoitov wrote: > On Tue, Oct 15, 2024 at 7:42 PM Tianchen Ding <dtcccc@linux.alibaba.com> wrote: >> >> Save the searching time during bpf_scx_init. >> >> Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com> >> --- >> 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.
On Wed, Oct 16, 2024 at 6:57 PM Tianchen Ding <dtcccc@linux.alibaba.com> wrote: > > On 2024/10/17 00:57, Alexei Starovoitov wrote: > > On Tue, Oct 15, 2024 at 7:42 PM Tianchen Ding <dtcccc@linux.alibaba.com> wrote: > >> > >> Save the searching time during bpf_scx_init. > >> > >> Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com> > >> --- > >> 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. Definitely shouldn't add run-time checks. Build check may work, but feels overkill at this point.
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]); return 0; }
Save the searching time during bpf_scx_init. Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com> --- kernel/sched/ext.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-)