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 18F5A1F2B8B for ; Mon, 3 Mar 2025 10:06:30 +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=1740996391; cv=none; b=e+yHaqjq2Cqy2zwOziw+9DS9MeuJkZ7NLhrTH5ejPJ17ZQi7h+aK+nwbDX1lsdHhUKij8EeJunq81Nk5gBfatbvbxBFHPuv3kXjXI01+vwg9bcCgc0fPBvb0lzCVoQ1qGa3oM0oZxDbmMMgQlqD2FvdFoe8O+GCEmo3N3UO6OOI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740996391; c=relaxed/simple; bh=ZJEojTWuFXiKxPY412FY66l7Kl1r/YJf053Gi49maqU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NFXXaixcseZQ8LcC5PPAGhq9DlWc6SXidTEz8lC9oL/g3ujBnmMP/Gmd9u4/Hf4HRhr2Y0nrlXU5EcdRBLgUiGuoDDxWxaYGMuiMqTxUKFvk/R0i3oKdEFJJr/xei9mzHPJdwGafzHaPVU3xtnt39ncp6U61wBCDieI+eFKceTg= 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 AE140113E; Mon, 3 Mar 2025 02:06:43 -0800 (PST) Received: from [192.168.178.6] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E59D03F66E; Mon, 3 Mar 2025 02:06:28 -0800 (PST) Message-ID: Date: Mon, 3 Mar 2025 11:06:27 +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: BUG Report: Fork benchmark drop by 30% on aarch64 To: Hagar Hemdan Cc: abuehaze@amazon.com, linux-kernel@vger.kernel.org, wuchi.zero@gmail.com References: <20250205151026.13061-1-hagarhem@amazon.com> <4a9cc5ab-c538-4427-8a7c-99cb317a283f@arm.com> <20250207110754.GA10452@amazon.com> <1ca758c7-b6ab-4880-9cc7-217093a30bbb@arm.com> <20250210213155.GA649@amazon.com> <4b48fd24-6cd5-474c-bed8-3faac096fd58@arm.com> <20250211214019.GA15530@amazon.com> <75503128-c898-4da7-ab99-55f4ef6e2add@arm.com> <5f92761b-c7d4-4b96-9398-183a5bf7556a@arm.com> <20250228193945.GA13237@amazon.com> From: Dietmar Eggemann Content-Language: en-US In-Reply-To: <20250228193945.GA13237@amazon.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 28/02/2025 20:39, Hagar Hemdan wrote: > On Mon, Feb 17, 2025 at 11:51:45PM +0100, Dietmar Eggemann wrote: >> On 13/02/2025 19:55, Dietmar Eggemann wrote: >>> On 11/02/2025 22:40, Hagar Hemdan wrote: >>>> On Tue, Feb 11, 2025 at 05:27:47PM +0100, Dietmar Eggemann wrote: >>>>> On 10/02/2025 22:31, Hagar Hemdan wrote: >>>>>> On Mon, Feb 10, 2025 at 11:38:51AM +0100, Dietmar Eggemann wrote: >>>>>>> On 07/02/2025 12:07, Hagar Hemdan wrote: >>>>>>>> On Fri, Feb 07, 2025 at 10:14:54AM +0100, Dietmar Eggemann wrote: [...] >> './Run -c 4 spawn' on AWS instance (m7gd.16xlarge) with v6.13, 'mem=16G >> maxcpus=4 nr_cpus=4' and Ubuntu '22.04.5 LTS': >> >> CFG_SCHED_AUTOGROUP | sched_ag_enabled | eff6c8ce8d4d | Fork (lps) >> >> y 1 y 21005 (27120 **) >> y 0 y 21059 (27012 **) >> n - y 21299 >> y 1 n 27745 * >> y 0 n 27493 * >> n - n 20928 >> >> (*) So here the higher numbers are only achieved when >> 'sched_autogroup_exit_task() -> sched_move_task() -> >> sched_change_group() is called for the 'spawn' tasks. >> >> (**) When I apply the fix from >> https://lkml.kernel.org/r/4a9cc5ab-c538-4427-8a7c-99cb317a283f@arm.com. > > This is currently impacting our kernel, do you > have any concerns to submit this fix upstream? Will send it out after the analysis now done. See the other email from today.