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Fri, 24 Oct 2025 11:36:00 -0700 (PDT) From: Xie Yuanbin To: linux@armlinux.org.uk, mathieu.desnoyers@efficios.com, paulmck@kernel.org, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, davem@davemloft.net, andreas@gaisler.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, luto@kernel.org, peterz@infradead.org, acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, anna-maria@linutronix.de, frederic@kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, qq570070308@gmail.com, thuth@redhat.com, riel@surriel.com, akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, segher@kernel.crashing.org, ryan.roberts@arm.com, max.kellermann@ionos.com, urezki@gmail.com, nysal@linux.ibm.com Cc: x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-perf-users@vger.kernel.org, will@kernel.org Subject: [PATCH 2/3] Provide and use an always inline version of finish_task_switch Date: Sat, 25 Oct 2025 02:35:40 +0800 Message-ID: <20251024183541.68955-1-qq570070308@gmail.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251024182628.68921-1-qq570070308@gmail.com> References: <20251024182628.68921-1-qq570070308@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" finish_task_switch is called during context switching, inlining it can bring some performance benefits. Add an always inline version `finish_task_switch_ainline` to be called during context switching, and keep the original version for being called elsewhere, so as to take into account the size impact. Signed-off-by: Xie Yuanbin --- kernel/sched/core.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 1842285eac1e..6cb3f57c4d35 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5069,21 +5069,21 @@ prepare_task_switch(struct rq *rq, struct task_stru= ct *prev, * Note that we may have delayed dropping an mm in context_switch(). If * so, we finish that here outside of the runqueue lock. (Doing it * with the lock held can cause deadlocks; see schedule() for * details.) * * The context switch have flipped the stack from under us and restored the * local variables which were saved when this task called schedule() in the * past. 'prev =3D=3D current' is still correct but we need to recalculate= this_rq * because prev may have moved to another CPU. */ -static struct rq *finish_task_switch(struct task_struct *prev) +static __always_inline struct rq *finish_task_switch_ainline(struct task_s= truct *prev) __releases(rq->lock) { struct rq *rq =3D this_rq(); struct mm_struct *mm =3D rq->prev_mm; unsigned int prev_state; =20 /* * The previous task will have left us with a preempt_count of 2 * because it left us after: * @@ -5153,20 +5153,25 @@ static struct rq *finish_task_switch(struct task_st= ruct *prev) =20 /* Task is done with its stack. */ put_task_stack(prev); =20 put_task_struct_rcu_user(prev); } =20 return rq; } =20 +static struct rq *finish_task_switch(struct task_struct *prev) +{ + return finish_task_switch_ainline(prev); +} + /** * schedule_tail - first thing a freshly forked thread must call. * @prev: the thread we just switched away from. */ asmlinkage __visible void schedule_tail(struct task_struct *prev) __releases(rq->lock) { /* * New tasks start with FORK_PREEMPT_COUNT, see there and * finish_task_switch() for details. @@ -5247,21 +5252,21 @@ context_switch(struct rq *rq, struct task_struct *p= rev, =20 /* switch_mm_cid() requires the memory barriers above. */ switch_mm_cid(rq, prev, next); =20 prepare_lock_switch(rq, next, rf); =20 /* Here we just switch the register state and the stack. */ switch_to(prev, next, prev); barrier(); =20 - return finish_task_switch(prev); + return finish_task_switch_ainline(prev); } =20 /* * nr_running and nr_context_switches: * * externally visible scheduler statistics: current number of runnable * threads, total number of context switches performed since bootup. */ unsigned int nr_running(void) { --=20 2.51.0