From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 16E3A1E525 for ; Mon, 3 Jun 2024 15:57:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717430246; cv=none; b=OzSn3hJ98BbIWRcQrsqKj2rGMRGwW4NUF51wZ8XLxmFEvJqOo5/jbWqsx1AIPfl4GU04SLhWtShYgFIlFIMaJbHR5IBgrZg4kPJzMIfIWoSA38w21Q4xbGqXeKfMVIo17kz5+qB6XQkNsB7U386dKSH4QRIEatRaSA5QkX31vnY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717430246; c=relaxed/simple; bh=2bqRqWYiVIR8h9mv7pcxawhYKpjJqXxZgnm3Padn8pM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TIvuTn0IqMAuLXgdOEC9ewklKS4yC7nwL1DZ3hTn8eWykRfMeVZkE4w1D9yQj+awnfHPCBZ6/QoEMKpqxgfAEBNNopfYNk3R8fN7EapiYnDf3KCCdLp66XsinFrG/Ck4ECzLJ83UreObz3FOsZ2iPgW6IuT4qclvl1Q9ahzgYqI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 38D3B1042; Mon, 3 Jun 2024 08:57:41 -0700 (PDT) Received: from [10.57.87.208] (unknown [10.57.87.208]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6A28B3F64C; Mon, 3 Jun 2024 08:57:16 -0700 (PDT) Message-ID: <788a0c8a-79b9-4a06-9739-8b62498bde90@arm.com> Date: Mon, 3 Jun 2024 16:57:15 +0100 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: [RFC][PATCH 08/10] sched/fair: Implement delayed dequeue To: Peter Zijlstra , Luis Machado Cc: linux-kernel@vger.kernel.org References: <20240405102754.435410987@infradead.org> <20240405110010.631664251@infradead.org> <3888d7c8-660e-479c-8c10-8295204e5f36@arm.com> <1461277e-af68-41e7-947c-9178b55810b1@arm.com> <20240425104220.GE21980@noisy.programming.kicks-ass.net> <20240425114949.GH12673@noisy.programming.kicks-ass.net> <20240426093241.GI12673@noisy.programming.kicks-ass.net> <20240523084548.GI40213@noisy.programming.kicks-ass.net> <20240523093338.GJ40213@noisy.programming.kicks-ass.net> Content-Language: en-US From: Hongyan Xia In-Reply-To: <20240523093338.GJ40213@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 23/05/2024 10:33, Peter Zijlstra wrote: > On Thu, May 23, 2024 at 10:06:04AM +0100, Luis Machado wrote: > >> Booting the kernel with NO_DELAY_DEQUEUE (default to false), things work fine. Then >> if I switch to DELAY_DEQUEUE at runtime, things start using a lot more power. >> >> The interesting bit is if I switch to NO_DELAY_DEQUEUE again at runtime, things don't >> go back to normal. Rather they stay the same, using a lot more energy. > > Ooh, cute.. weird. I'll try and see if we leak state somehow. Hi. I'm working on uclamp anyway so I just gave this series (and all fixes mentioned in this thread) a go. It seems after running with this series for a while, suddenly uclamp_max no longer works. Running a task with uclamp_max of 110 still sees an rq uclamp_max of 1024. Also weirdly, the PELT signal of that uclamp_max is completely broken. It goes up to a very high value and then suddenly drops to almost 0 from time to time. I wonder if the reason Luis saw that is because he was the first one to run delayed dequeue with uclamp. I'm not familiar enough with the series to know how it could possibly affect uclamp so investigating in this front may be worth trying. Maybe some leaked uclamp state on the rq?