From: Zhan Xusheng Date: Wed, 14 Jan 2026 09:00:35 +0000 (+0800) Subject: sched/fair: Fix math notation errors in avg_vruntime comment X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=553255cc857c08d72658b57d01c04f76cde9a83a;p=thirdparty%2Fkernel%2Flinux.git 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 Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260114090035.19033-1-zhanxusheng@xiaomi.com --- diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ebee20f75fa02..af120e88720f7 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.