linux-kernel - [tip: sched/core] sched/fair: Fix math notation errors in avg

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <176851345880.510.10598609220244806180.tip-bot2@tip-bot2>
Date: Thu, 15 Jan 2026 21:44:18 -0000
From: "tip-bot2 for Zhan Xusheng" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Zhan Xusheng <zhanxusheng@...omi.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/fair: Fix math notation errors in
 avg_vruntime comment

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     553255cc857c08d72658b57d01c04f76cde9a83a
Gitweb:        https://git.kernel.org/tip/553255cc857c08d72658b57d01c04f76cde9a83a
Author:        Zhan Xusheng <zhanxusheng1024@...il.com>
AuthorDate:    Wed, 14 Jan 2026 17:00:35 +08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 15 Jan 2026 22:41:26 +01:00

sched/fair: Fix math notation errors in avg_vruntime comment

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 <zhanxusheng@...omi.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://patch.msgid.link/20260114090035.19033-1-zhanxusheng@xiaomi.com
---
 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 ebee20f..af120e8 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -613,7 +613,7 @@ static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
  *
  *   \Sum lag_i = 0
  *   \Sum w_i * (V - v_i) = 0
- *   \Sum w_i * V - w_i * v_i = 0
+ *   \Sum (w_i * V - w_i * v_i) = 0
  *
  * From which we can solve an expression for V in v_i (which we have in
  * se->vruntime):
@@ -648,7 +648,7 @@ static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
  *              \Sum w_i := cfs_rq->sum_weight
  *
  * 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.