Commit 477174ac authored by David Carlier's avatar David Carlier Committed by Tejun Heo
Browse files

sched_ext: Optimize sched_ext_entity layout for cache locality 



Reorder struct sched_ext_entity to place ops_state, ddsp_dsq_id, and
ddsp_enq_flags immediately after dsq. These fields are accessed together
in the do_enqueue_task() and finish_dispatch() hot paths but were
previously spread across three different cache lines. Grouping them on
the same cache line reduces cache misses on every enqueue and dispatch
operation.

Signed-off-by: default avatarDavid Carlier <devnexen@gmail.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 658ad225

include/linux/sched/ext.h

+3 −3
Original line number Diff line number Diff line
@@ -163,6 +163,9 @@ struct scx_dsq_list_node { 
 */

struct sched_ext_entity {

	struct scx_dispatch_q	*dsq;

	atomic_long_t		ops_state;

	u64			ddsp_dsq_id;

	u64			ddsp_enq_flags;

	struct scx_dsq_list_node dsq_list;	/* dispatch order */

	struct rb_node		dsq_priq;	/* p->scx.dsq_vtime order */

	u32			dsq_seq;
@@ -174,7 +177,6 @@ struct sched_ext_entity { 
	s32			selected_cpu;

	u32			kf_mask;	/* see scx_kf_mask above */

	struct task_struct	*kf_tasks[2];	/* see SCX_CALL_OP_TASK() */

	atomic_long_t		ops_state;



	struct list_head	runnable_node;	/* rq->scx.runnable_list */

	unsigned long		runnable_at;
@@ -182,8 +184,6 @@ struct sched_ext_entity { 
#ifdef CONFIG_SCHED_CORE

	u64			core_sched_at;	/* see scx_prio_less() */

#endif

	u64			ddsp_dsq_id;

	u64			ddsp_enq_flags;



	/* BPF scheduler modifiable fields */