From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6CDF013D258 for ; Thu, 11 Apr 2024 07:28:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712820490; cv=none; b=mDJ1cHl6HFDtiJyRQIOILIifrLlIax+BPGbIl5+0JyRRaX1S8DoUO8iy5gR0xOtmSNj55Uw1IardJD04ulsBUed+Ktr50zpEBlRhIDlpDBEvcDBijUtJtxzsQVUYY6mCcPvTKXJDxyUCtk3+Mo39VgdtZ9hI0xwfDIrJ6Cx3PPc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712820490; c=relaxed/simple; bh=nJ9e82oM4BnyJLrP/ege9wPr9McFFMBjRzqcj53itJ4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=I6OeYXmCoqwFBhSnL8b0vkkMRHPI5P+tIH6lHnci6hvHAE12smiek1aPPRd2yeExB7qECM3XXR8f4zXclDUtP+berXybuzIhDuU7oW/qqerLTqc7H02Fnag5G5n5mD5I6a5ecjDWJ90igAQHg+O8ugp1mf3dtGwjP1FpJ89KhdQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=E7MuGdwY; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="E7MuGdwY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18ADAC433C7; Thu, 11 Apr 2024 07:28:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1712820490; bh=nJ9e82oM4BnyJLrP/ege9wPr9McFFMBjRzqcj53itJ4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=E7MuGdwYhBo/xPrK3+whmdA+xFQAagWPAbLVnC10x3bPGGEWbGjpwzFixR5aFVCA/ IYUe1teVKkBaXxvYO9oicOC7QCslJq/FYQiuOCsnNOe8jDzhqt+YXOxK8Iu4B+4P9O nF0VDd6WTEUk2B7MvsNI1RmUXeJZjd2W76dr3ms+qZS8Hmd+ZZ145GzS9ec2NXWVdz rjnB/paQ3uTMIWN1F0QgMM5EXICITSicZY1IzpIpyAVeAfoQYFJWt5pG6Gz2AgTiKb O8bd2sXBUsqgplwGIzdAxnxmi5l+h770PKRZBl56a2yECvMp/aZuDfnqLiK6OyrEZ0 LLnugoB+0g6pw== Message-ID: <6db95fce-842e-4b99-bc6c-059fe655905f@kernel.org> Date: Thu, 11 Apr 2024 09:28:04 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V6 1/6] sched/fair: Add trivial fair server Content-Language: en-US, pt-BR, it-IT To: Peter Zijlstra Cc: Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , linux-kernel@vger.kernel.org, Luca Abeni , Tommaso Cucinotta , Thomas Gleixner , Joel Fernandes , Vineeth Pillai , Shuah Khan , Phil Auld , Suleiman Souhlal , Youssef Esmat References: <20240410172423.GB30852@noisy.programming.kicks-ass.net> From: Daniel Bristot de Oliveira In-Reply-To: <20240410172423.GB30852@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/10/24 19:24, Peter Zijlstra wrote: > On Fri, Apr 05, 2024 at 07:28:00PM +0200, Daniel Bristot de Oliveira wrote: >> From: Peter Zijlstra >> >> Use deadline servers to service fair tasks. >> >> This patch adds a fair_server deadline entity which acts as a container >> for fair entities and can be used to fix starvation when higher priority >> (wrt fair) tasks are monopolizing CPU(s). >> >> Signed-off-by: Peter Zijlstra (Intel) >> Signed-off-by: Daniel Bristot de Oliveira >> --- >> kernel/sched/core.c | 24 ++++++++++++++++-------- >> kernel/sched/deadline.c | 23 +++++++++++++++++++++++ >> kernel/sched/fair.c | 25 +++++++++++++++++++++++++ >> kernel/sched/sched.h | 4 ++++ >> 4 files changed, 68 insertions(+), 8 deletions(-) >> >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index 7019a40457a6..04e2270487b7 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -6007,6 +6007,14 @@ static void put_prev_task_balance(struct rq *rq, struct task_struct *prev, >> #endif >> >> put_prev_task(rq, prev); >> + >> + /* >> + * We've updated @prev and no longer need the server link, clear it. >> + * Must be done before ->pick_next_task() because that can (re)set >> + * ->dl_server. >> + */ >> + if (prev->dl_server) >> + prev->dl_server = NULL; >> } >> >> /* >> @@ -6037,6 +6045,13 @@ __pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) >> p = pick_next_task_idle(rq); >> } >> >> + /* >> + * This is a normal CFS pick, but the previous could be a DL pick. >> + * Clear it as previous is no longer picked. >> + */ >> + if (prev->dl_server) >> + prev->dl_server = NULL; >> + >> /* >> * This is the fast path; it cannot be a DL server pick; >> * therefore even if @p == @prev, ->dl_server must be NULL. >> @@ -6050,14 +6065,6 @@ __pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) >> restart: >> put_prev_task_balance(rq, prev, rf); >> >> - /* >> - * We've updated @prev and no longer need the server link, clear it. >> - * Must be done before ->pick_next_task() because that can (re)set >> - * ->dl_server. >> - */ >> - if (prev->dl_server) >> - prev->dl_server = NULL; >> - >> for_each_class(class) { >> p = class->pick_next_task(rq); >> if (p) > > This bit seems like a fix for 63ba8422f876 ("sched/deadline: Introduce > deadline servers"), should it be a separate patch? It was actually reported in a separated patch as a pre-review of this series. So I think you can pick them as fixes already from there, and add the fixes tag? https://lore.kernel.org/lkml/20240313012451.1693807-2-joel@joelfernandes.org/ https://lore.kernel.org/lkml/20240313012451.1693807-3-joel@joelfernandes.org/ Also add the Reviewed-by me... -- Daniel