From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay4-d.mail.gandi.net (relay4-d.mail.gandi.net [217.70.183.196]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 85A7C395AC4 for ; Thu, 18 Jun 2026 08:24:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.196 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781771084; cv=none; b=RgVWVGC8B9D/J8nPNvNJzr7NeCi9PnpcXdM2XoRJQ/bSOfLpenZ0zEU6l3XpuCyPx43/bfSN22/OEpzz0Aq+27EtgjXxPe1w5OK4gJrk4SR1BGsBOfvKgTTuFvxjYIJeyB+wz1d3Fhi2bsb8il8irMsAiDyNoo9Xj3sxbuqTOHM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781771084; c=relaxed/simple; bh=HTot9CEQuCFomFdqYBOWQLzjT9WKhQ4NW17xsFkpDNA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=IKAUYDNjMXFgP2hf8tzYnkimjo63FkcolUiIjJDTA8dFLGbTsEG7EkA4OzslMVO0+NcBeuz8vg1ymHnagkq+gUxbr6Kq+W7L8M8OGylheTk//j1nj1Ut1c9//VfV015AzjsBojrDJCew2BYK4WMu/Vj5tasjvGlA1w6OegnFoAU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xenomai.org; spf=pass smtp.mailfrom=xenomai.org; dkim=pass (2048-bit key) header.d=xenomai.org header.i=@xenomai.org header.b=Emym/QeN; arc=none smtp.client-ip=217.70.183.196 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xenomai.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xenomai.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=xenomai.org header.i=@xenomai.org header.b="Emym/QeN" Received: by mail.gandi.net (Postfix) with ESMTPSA id B29CF3E9B9; Thu, 18 Jun 2026 08:24:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xenomai.org; s=gm1; t=1781771079; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=xWq6Mk75RcmLB72M/AEC6Z2y1X3J4Th5nBDRbBtjJvo=; b=Emym/QeNedwvOS6dQr2ZMlSHPBc6PMTOGZeE/VNvGDzfnkUgS90PwJpOfO+SFGqAo/o00Y XbvYkv/3AM7Ovs6EPxtlTqQBovJj5t+haXvtup2TeR1QSoZRaphILFckCTpT2roIaxA0aP Bp64g+fcXLXTulucJWoPYfBz+DwP3ksA9NQhBRyM35waoGa0FFhuVbBa1uIGIoH2dw3U1s S/4IYLaf+jSw+EbPa1wYDbEP5VZoe6kk5Bm0BG6SjLWPjKOMdYgSts4P9Kuc9VgkHxyuAK 8k8m0l/2AYfka27/uP/T8AQ4QMJXTYoZMUuvpq8UzH0PSoOPz/6lXHGPjx4KvQ== From: Philippe Gerum To: Jan Kiszka Cc: xenomai@lists.linux.dev Subject: Re: [PATCH v1 1/2] evl/sched: core: introduce schedule out handler In-Reply-To: <58885755-a25b-4b71-86f9-166d0428990e@siemens.com> (Jan Kiszka's message of "Thu, 18 Jun 2026 10:04:09 +0200") References: <20260617142050.477809-1-rpm@xenomai.org> <20260617142050.477809-2-rpm@xenomai.org> <87ik7gs367.fsf@xenomai.org> <58885755-a25b-4b71-86f9-166d0428990e@siemens.com> User-Agent: mu4e 1.12.12; emacs 30.2 Date: Thu, 18 Jun 2026 10:24:39 +0200 Message-ID: <87y0gcqmrc.fsf@xenomai.org> Precedence: bulk X-Mailing-List: xenomai@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-GND-Sasl: rpm@xenomai.org X-GND-State: clean X-GND-Score: -100 X-GND-Cause: 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 Jan Kiszka writes: > On 18.06.26 09:44, Philippe Gerum wrote: >> Jan Kiszka writes: >> >>> On 17.06.26 16:20, Philippe Gerum wrote: >>>> From: Philippe Gerum >>>> >>>> Some scheduling classes may need a way to perform specific >>>> fixup/accounting work for a thread which is being scheduled out. We >>>> cannot rely on the sched_pick() handler for this since the first one >>>> to successfully pick a thread prevents other handlers down the class >>>> hierarchy to run. >>>> >>>> To address this issue, we introduce the sched_out() handler which is >>>> called for the current thread when scheduled out. This handler is >>>> invoked unconditionally when present prior to picking a new thread. >>>> >>>> Signed-off-by: Philippe Gerum >>>> --- >>>> include/evl/sched.h | 1 + >>>> kernel/evl/sched/core.c | 20 +++++++++++++------- >>>> 2 files changed, 14 insertions(+), 7 deletions(-) >>>> >>>> diff --git a/include/evl/sched.h b/include/evl/sched.h >>>> index ae9690860146..cc824c28004b 100644 >>>> --- a/include/evl/sched.h >>>> +++ b/include/evl/sched.h >>>> @@ -120,6 +120,7 @@ struct evl_sched_class { >>>> void (*sched_dequeue)(struct evl_thread *thread); >>>> void (*sched_requeue)(struct evl_thread *thread); >>>> struct evl_thread *(*sched_pick)(struct evl_rq *rq); >>>> + void (*sched_out)(struct evl_thread *thread); >>>> void (*sched_yield)(struct evl_thread *thread); >>>> void (*sched_migrate)(struct evl_thread *thread, >>>> struct evl_rq *rq); >>>> diff --git a/kernel/evl/sched/core.c b/kernel/evl/sched/core.c >>>> index d1d025e06a5d..7127d4e52df9 100644 >>>> --- a/kernel/evl/sched/core.c >>>> +++ b/kernel/evl/sched/core.c >>>> @@ -773,7 +773,8 @@ static inline void set_next_running(struct evl_rq *rq, >>>> evl_stop_timer(&rq->rrbtimer); >>>> } >>>> >>>> -static struct evl_thread *__pick_next_thread(struct evl_rq *rq) >>>> +static __always_inline struct evl_thread * >>>> +__pick_next_thread(struct evl_rq *rq) >>>> { >>>> struct evl_sched_class *sched_class; >>>> struct evl_thread *curr = rq->curr; >>>> @@ -821,8 +822,14 @@ static struct evl_thread *__pick_next_thread(struct evl_rq *rq) >>>> /* rq->curr->lock + rq->lock held, hard irqs off. */ >>>> static struct evl_thread *pick_next_thread(struct evl_rq *rq) >>>> { >>>> - struct evl_thread *next = __pick_next_thread(rq); >>>> + struct evl_thread *next, *prev = rq->curr; >>>> + struct evl_sched_class *prev_class = prev->sched_class; >>>> >>>> + if (prev_class->sched_out) >>>> + prev_class->sched_out(prev); >>>> + >>>> + next = __pick_next_thread(rq); >>>> + trace_evl_pick_thread(next); >>>> set_next_running(rq, next); >>>> >>>> return next; >>>> @@ -972,21 +979,20 @@ void __evl_schedule(void) /* oob or/and hard irqs off (CPU migration-safe) */ >>>> return; >>>> } >>>> >>>> + prev = curr; >>>> next = pick_next_thread(this_rq); >>>> - trace_evl_pick_thread(next); >>>> - if (next == curr) { >>>> - if (unlikely(next->state & EVL_T_ROOT)) { >>>> + if (next == prev) { >>>> + if (unlikely(prev->state & EVL_T_ROOT)) { >>>> if (this_rq->local_flags & RQ_TPROXY) >>>> evl_notify_proxy_tick(this_rq); >>>> if (this_rq->local_flags & RQ_TDEFER) >>>> evl_program_local_tick(&evl_mono_clock); >>>> } >>>> raw_spin_unlock(&this_rq->lock); >>>> - raw_spin_unlock_irqrestore(&curr->lock, flags); >>>> + raw_spin_unlock_irqrestore(&prev->lock, flags); >>>> return; >>>> } >>>> - >>>> - prev = curr; >>> >>> This hunk subtly look like a pure cosmetic change, without any logical >>> impact. If it does have one which I missed, it should be explained in >>> the commit message at least. >>> >> >> It has none, as mentioned earlier in a previous post. The point of this >> change is to clarify the naming, introducing 'prev' as an alias to >> 'curr' in the swap sequence. So there is no point in documenting this. >> > > BTW, I would not make lock/unlock work against different variables > names, though they carry identical pointers. That is more confusing than > the current code. > Yes, that point is valid. But in that case, there is no point in even clarifying the rest either. Ok, dropping the whole thing together. -- Philippe.