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 5A3A420D4FC for ; Mon, 10 Nov 2025 13:55:43 +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=1762782945; cv=none; b=kRdDpQR0yceuZqNPOqKT3uFMFqY3HbNt8tYRe4QrItmKChNSyFDSIVDRxukQ7NbuBQX4KCbox1hCgHsjaTZ/hMoJGJCqDZjrRGGSx4IQW5rca3LdbaV/Nv4Me+s241MhR5sYJZ1RQm7Xtn5pSJeZcVmtxBTUtbbgMw/1HxDnQz0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762782945; c=relaxed/simple; bh=Q55XP2cihs0ttF7sccUQCdpYM2FPw+v4l8tiSBLfKss=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SMJ/dIEhpCYpVXsBy9nUxFGwmQaWvfsKYNboqlIo74Dx5LVXUCAPFjRrlRkbbUKDBZ9qXRQ8nCty19iCdQCM+h9qEnGQieDi4br7PkP/ntXecvnxqfqzIOLJcmvOBpq+myJhbpH0HQU82laLKooo2bPANFyuK7536yowm0DL5RI= 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 1D917FEC; Mon, 10 Nov 2025 05:55:35 -0800 (PST) Received: from [10.57.88.175] (unknown [10.57.88.175]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6E2EB3F66E; Mon, 10 Nov 2025 05:55:40 -0800 (PST) Message-ID: <341aef79-43fd-43a6-b5b7-ad4689ba394e@arm.com> Date: Mon, 10 Nov 2025 14:55:40 +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: [PATCH 4/4] sched/fair: Proportional newidle balance To: Peter Zijlstra , Chris Mason , Joseph Salisbury , Adam Li , Hazem Mohamed Abuelfotoh , Josh Don Cc: mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org References: <20251107160645.929564468@infradead.org> <20251107161739.770122091@infradead.org> Content-Language: en-GB From: Dietmar Eggemann In-Reply-To: <20251107161739.770122091@infradead.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 07.11.25 17:06, Peter Zijlstra wrote: > Add a randomized algorithm that runs newidle balancing proportional to > its success rate. > > This improves schbench significantly: > > 6.18-rc4: 2.22 Mrps/s > 6.18-rc4+revert: 2.04 Mrps/s > 6.18-rc4+revert+random: 2.18 Mrps/S > > Conversely, per Adam Li this affects SpecJBB slightly, reducing it by 1%: > > 6.17: -6% > 6.17+revert: 0% > 6.17+revert+random: -1% > > Signed-off-by: Peter Zijlstra (Intel) Results with OLTP 'hammerdb - mysqld' on Arm64 VMs NOPM P50 latency 6.18-rc4 baseline baseline 6.18-rc4+revert-155213a2aed4 +13% -8.8% 6.18-rc4+patchset +11% -8.2% 6.18-rc4+patchset+NO_NI_RANDOM +13% -8.6% Pretty consistent with the results on the previous version. Although I hadn't tested NI_TARGET+NI_RANDOM back then. http://lkml.kernel.org/r/f6379aa6-459d-4205-96ea-9848e55d7f9c@arm.com In case (pure wakeup) schbench configs are the only workloads profiting from NI_RANDOM, make NO_NI_RANDOM the default? Reviewed-by: Dietmar Eggemann Tested-by: Dietmar Eggemann [...]