[PATCH v6 6/6] sched_ext: Use time helpers in BPF schedulers

[Changwoo Min <multics69@gmail.com>]

Modify the BPF schedulers to use time helpers defined in common.bpf.h

Signed-off-by: Changwoo Min <changwoo@igalia.com>
---
 tools/sched_ext/scx_central.bpf.c |  5 -----
 tools/sched_ext/scx_flatcg.bpf.c  | 11 +++--------
 tools/sched_ext/scx_simple.bpf.c  |  5 -----
 3 files changed, 3 insertions(+), 18 deletions(-)

diff --git a/tools/sched_ext/scx_central.bpf.c b/tools/sched_ext/scx_central.bpf.c
index ea1d853b9dd4..c3b6998ea83e 100644
--- a/tools/sched_ext/scx_central.bpf.c
+++ b/tools/sched_ext/scx_central.bpf.c
@@ -87,11 +87,6 @@ struct {
 	__type(value, struct central_timer);
 } central_timer SEC(".maps");
 
-static bool vtime_before(u64 a, u64 b)
-{
-	return (s64)(a - b) < 0;
-}
-
 s32 BPF_STRUCT_OPS(central_select_cpu, struct task_struct *p,
 		   s32 prev_cpu, u64 wake_flags)
 {
diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
index 85e33e45f818..2735ec25e511 100644
--- a/tools/sched_ext/scx_flatcg.bpf.c
+++ b/tools/sched_ext/scx_flatcg.bpf.c
@@ -137,11 +137,6 @@ static u64 div_round_up(u64 dividend, u64 divisor)
 	return (dividend + divisor - 1) / divisor;
 }
 
-static bool vtime_before(u64 a, u64 b)
-{
-	return (s64)(a - b) < 0;
-}
-
 static bool cgv_node_less(struct bpf_rb_node *a, const struct bpf_rb_node *b)
 {
 	struct cgv_node *cgc_a, *cgc_b;
@@ -920,14 +915,14 @@ void BPF_STRUCT_OPS(fcg_cgroup_move, struct task_struct *p,
 		    struct cgroup *from, struct cgroup *to)
 {
 	struct fcg_cgrp_ctx *from_cgc, *to_cgc;
-	s64 vtime_delta;
+	s64 delta;
 
 	/* find_cgrp_ctx() triggers scx_ops_error() on lookup failures */
 	if (!(from_cgc = find_cgrp_ctx(from)) || !(to_cgc = find_cgrp_ctx(to)))
 		return;
 
-	vtime_delta = p->scx.dsq_vtime - from_cgc->tvtime_now;
-	p->scx.dsq_vtime = to_cgc->tvtime_now + vtime_delta;
+	delta = vtime_delta(p->scx.dsq_vtime, from_cgc->tvtime_now);
+	p->scx.dsq_vtime = to_cgc->tvtime_now + delta;
 }
 
 s32 BPF_STRUCT_OPS_SLEEPABLE(fcg_init)
diff --git a/tools/sched_ext/scx_simple.bpf.c b/tools/sched_ext/scx_simple.bpf.c
index 31f915b286c6..6561d400ae6d 100644
--- a/tools/sched_ext/scx_simple.bpf.c
+++ b/tools/sched_ext/scx_simple.bpf.c
@@ -52,11 +52,6 @@ static void stat_inc(u32 idx)
 		(*cnt_p)++;
 }
 
-static inline bool vtime_before(u64 a, u64 b)
-{
-	return (s64)(a - b) < 0;
-}
-
 s32 BPF_STRUCT_OPS(simple_select_cpu, struct task_struct *p, s32 prev_cpu, u64 wake_flags)
 {
 	bool is_idle = false;
-- 
2.47.1