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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483b82392cfsm16166445e9.3.2026.02.23.21.56.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Feb 2026 21:56:41 -0800 (PST) From: David Carlier To: Tejun Heo , David Vernet Cc: linux-kernel@vger.kernel.org, David Carlier Subject: [PATCH] sched_ext: optimize sched_ext_entity layout for cache locality Date: Tue, 24 Feb 2026 05:56:37 +0000 Message-ID: <20260224055637.16956-1-devnexen@gmail.com> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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: David Carlier --- include/linux/sched/ext.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h index bcb962d5ee7d..80e70a9642fd 100644 --- a/include/linux/sched/ext.h +++ b/include/linux/sched/ext.h @@ -162,6 +162,9 @@ 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; @@ -173,7 +176,6 @@ 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; @@ -181,8 +183,6 @@ 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 */ -- 2.51.0