sched/ext: Add BPF function to fetch rq

rq contains many useful fields to implement a custom scheduler. For
example, various clock signals like clock_task and clock_pelt can be
used to track load. It also contains stats in other sched_classes, which
are useful to drive scheduling decisions in ext.

tj: Put the new helper below scx_bpf_task_*() helpers.

Signed-off-by: Hongyan Xia <hongyan.xia2@arm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 33bfb5a88b480458dabe6a5a9e5905e6afca13de..525102f3ff5be396d780c4fc292f9389c9fbaa7e 100644 (file)
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -6113,6 +6113,18 @@ __bpf_kfunc s32 scx_bpf_task_cpu(const struct task_struct *p)
        return task_cpu(p);
 }
 
+/**
+ * scx_bpf_cpu_rq - Fetch the rq of a CPU
+ * @cpu: CPU of the rq
+ */
+__bpf_kfunc struct rq *scx_bpf_cpu_rq(s32 cpu)
+{
+       if (!ops_cpu_valid(cpu, NULL))
+               return NULL;
+
+       return cpu_rq(cpu);
+}
+
 __bpf_kfunc_end_defs();
 
 BTF_KFUNCS_START(scx_kfunc_ids_any)
@@ -6137,6 +6149,7 @@ BTF_ID_FLAGS(func, scx_bpf_pick_idle_cpu, KF_RCU)
 BTF_ID_FLAGS(func, scx_bpf_pick_any_cpu, KF_RCU)
 BTF_ID_FLAGS(func, scx_bpf_task_running, KF_RCU)
 BTF_ID_FLAGS(func, scx_bpf_task_cpu, KF_RCU)
+BTF_ID_FLAGS(func, scx_bpf_cpu_rq)
 BTF_KFUNCS_END(scx_kfunc_ids_any)
 
 static const struct btf_kfunc_id_set scx_kfunc_set_any = {

diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h
index dbbda0e35c5d167a61fa3218a209ec58dd319019..965d20324114b2e27a86923ec68a4454865f6292 100644 (file)
--- a/tools/sched_ext/include/scx/common.bpf.h
+++ b/tools/sched_ext/include/scx/common.bpf.h
@@ -57,6 +57,7 @@ s32 scx_bpf_pick_idle_cpu(const cpumask_t *cpus_allowed, u64 flags) __ksym;
 s32 scx_bpf_pick_any_cpu(const cpumask_t *cpus_allowed, u64 flags) __ksym;
 bool scx_bpf_task_running(const struct task_struct *p) __ksym;
 s32 scx_bpf_task_cpu(const struct task_struct *p) __ksym;
+struct rq *scx_bpf_cpu_rq(s32 cpu) __ksym;
 
 static inline __attribute__((format(printf, 1, 2)))
 void ___scx_bpf_bstr_format_checker(const char *fmt, ...) {}