[PATCH 09/12] sched_ext: Factor out scx_read_events()

Tejun Heo
2025-04-25T21:58:54Z

In prepration of moving event_stats_cpu into scx_sched, factor out
scx_read_events() out of scx_bpf_events() and update the in-kernel users -
scx_attr_events_show() and scx_dump_state() - to use scx_read_events()
instead of scx_bpf_events(). No observable behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
kernel/sched/ext.c | 45 ++++++++++++++++++++++++++-------------------
1 file changed, 26 insertions(+), 19 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index bbcd7c0f561e..885cd71a847e 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1651,7 +1651,7 @@ static DEFINE_PER_CPU(struct scx_event_stats, event_stats_cpu);
} while (0)

-static void scx_bpf_events(struct scx_event_stats *events, size_t events__sz);
+static void scx_read_events(struct scx_event_stats *events);

static enum scx_enable_state scx_enable_state(void)
{
@@ -4458,7 +4458,7 @@ static ssize_t scx_attr_events_show(struct kobject *kobj,
struct scx_event_stats events;
int at = 0;

- scx_bpf_events(&events, sizeof(events));
+ scx_read_events(&events);
at += scx_attr_event_show(buf, at, &events, SCX_EV_SELECT_CPU_FALLBACK);
at += scx_attr_event_show(buf, at, &events, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
at += scx_attr_event_show(buf, at, &events, SCX_EV_DISPATCH_KEEP_LAST);
@@ -5182,7 +5182,7 @@ static void scx_dump_state(struct scx_exit_info *ei, size_t dump_len)
dump_line(&s, "Event counters");
dump_line(&s, "--------------");

- scx_bpf_events(&events, sizeof(events));
+ scx_read_events(&events);
scx_dump_event(s, &events, SCX_EV_SELECT_CPU_FALLBACK);
scx_dump_event(s, &events, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
scx_dump_event(s, &events, SCX_EV_DISPATCH_KEEP_LAST);
@@ -7405,6 +7405,27 @@ __bpf_kfunc u64 scx_bpf_now(void)
return clock;
}

+static void scx_read_events(struct scx_event_stats *events)
+{
+ struct scx_event_stats *e_cpu;
+ int cpu;
+
+ /* Aggregate per-CPU event counters into @events. */
+ memset(events, 0, sizeof(*events));
+ for_each_possible_cpu(cpu) {
+ e_cpu = per_cpu_ptr(&event_stats_cpu, cpu);
+ scx_agg_event(events, e_cpu, SCX_EV_SELECT_CPU_FALLBACK);
+ scx_agg_event(events, e_cpu, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
+ scx_agg_event(events, e_cpu, SCX_EV_DISPATCH_KEEP_LAST);
+ scx_agg_event(events, e_cpu, SCX_EV_ENQ_SKIP_EXITING);
+ scx_agg_event(events, e_cpu, SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);
+ scx_agg_event(events, e_cpu, SCX_EV_REFILL_SLICE_DFL);
+ scx_agg_event(events, e_cpu, SCX_EV_BYPASS_DURATION);
+ scx_agg_event(events, e_cpu, SCX_EV_BYPASS_DISPATCH);
+ scx_agg_event(events, e_cpu, SCX_EV_BYPASS_ACTIVATE);
+ }
+}
+
/*
* scx_bpf_events - Get a system-wide event counter to
* @events: output buffer from a BPF program
@@ -7413,23 +7434,9 @@ __bpf_kfunc u64 scx_bpf_now(void)
__bpf_kfunc void scx_bpf_events(struct scx_event_stats *events,
size_t events__sz)
{
- struct scx_event_stats e_sys, *e_cpu;
- int cpu;
+ struct scx_event_stats e_sys;

- /* Aggregate per-CPU event counters into the system-wide counters. */
- memset(&e_sys, 0, sizeof(e_sys));
- for_each_possible_cpu(cpu) {
- e_cpu = per_cpu_ptr(&event_stats_cpu, cpu);
- scx_agg_event(&e_sys, e_cpu, SCX_EV_SELECT_CPU_FALLBACK);
- scx_agg_event(&e_sys, e_cpu, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
- scx_agg_event(&e_sys, e_cpu, SCX_EV_DISPATCH_KEEP_LAST);
- scx_agg_event(&e_sys, e_cpu, SCX_EV_ENQ_SKIP_EXITING);
- scx_agg_event(&e_sys, e_cpu, SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);
- scx_agg_event(&e_sys, e_cpu, SCX_EV_REFILL_SLICE_DFL);
- scx_agg_event(&e_sys, e_cpu, SCX_EV_BYPASS_DURATION);
- scx_agg_event(&e_sys, e_cpu, SCX_EV_BYPASS_DISPATCH);
- scx_agg_event(&e_sys, e_cpu, SCX_EV_BYPASS_ACTIVATE);
- }
+ scx_read_events(&e_sys);

/*
* We cannot entirely trust a BPF-provided size since a BPF program
--
2.49.0