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Wed, 14 Jan 2026 01:00:42 -0800 (PST) Received: from DESKTOP-MOQC9AF.mioffice.cn ([43.224.245.239]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35109d88f0esm1341160a91.5.2026.01.14.01.00.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Jan 2026 01:00:41 -0800 (PST) From: Zhan Xusheng X-Google-Original-From: Zhan Xusheng To: Peter Zijlstra Cc: Ingo Molnar , linux-sched@vger.kernel.org, linux-kernel@vger.kernel.org, Zhan Xusheng Subject: [PATCH] sched/fair: Fix math notation errors in avg_vruntime comment Date: Wed, 14 Jan 2026 17:00:35 +0800 Message-ID: <20260114090035.19033-1-zhanxusheng@xiaomi.com> X-Mailer: git-send-email 2.43.0 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" The avg_vruntime comment contains a couple of mathematical notation issues: - The summation over w_i * (V - v_i) is written in an ambiguous form - The delta term refers to v instead of v0, which is inconsistent with the code and preceding explanation Fix these to make the comment mathematically correct and consistent with the implementation. Signed-off-by: Zhan Xusheng --- kernel/sched/fair.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e71302282671..36c6009a0df4 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -576,7 +576,7 @@ static inline s64 entity_key(struct cfs_rq *cfs_rq, str= uct sched_entity *se) * * \Sum lag_i =3D 0 * \Sum w_i * (V - v_i) =3D 0 - * \Sum w_i * V - w_i * v_i =3D 0 + * \Sum (w_i * V - w_i * v_i) =3D 0 * * From which we can solve an expression for V in v_i (which we have in * se->vruntime): @@ -611,7 +611,7 @@ static inline s64 entity_key(struct cfs_rq *cfs_rq, str= uct sched_entity *se) * \Sum w_i :=3D cfs_rq->avg_load * * Since zero_vruntime closely tracks the per-task service, these - * deltas: (v_i - v), will be in the order of the maximal (virtual) lag + * deltas: (v_i - v0), will be in the order of the maximal (virtual) lag * induced in the system due to quantisation. * * Also, we use scale_load_down() to reduce the size. --=20 2.43.0