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 86B866FBF; Fri, 6 Dec 2024 03:56:41 +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=1733457403; cv=none; b=I2bfYO/GQNP8dO8XkyZSMUi22ijEslNxrj8VTMl7o92HFK+ETRE3MdED9+HC/lpTJY9qwhQYGysxT97P3eGe6SY0jArpuDZ6CTonwjlNVDgoQxmyAJuLSMwBxVcZrazRdUZ9i+yOxe7xkz/BKHbU8u5Pcq/DLX15DCF/L5CgmUE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733457403; c=relaxed/simple; bh=2OrVg2wTjxGzF3gX1FKhWEV4gZ2+cqniMAPHcV+eQlI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ME7htC8kwi4SIfV0zSeUP7mrU32LyuTDxbtOKeMm+ZKlqT3HdsiLt167Hwbl1Vrm9TYWpHSid6b1fLa2Bghsoor02SvhGOOx79iM2Z3lSjGCh4KQTqglSbdT7bZqwXR6+irWBDvvP6bBEUZCYuHL/25415tRLyBKjewLdREtjps= 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 2DF41169E; Thu, 5 Dec 2024 19:57:08 -0800 (PST) Received: from [10.163.50.12] (unknown [10.163.50.12]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 201353F58B; Thu, 5 Dec 2024 19:56:34 -0800 (PST) Message-ID: Date: Fri, 6 Dec 2024 09:26:32 +0530 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 v2 4/4] arm64: add a new document for the fine-tuning tips To: Huang Shijie , catalin.marinas@arm.com, will@kernel.org Cc: patches@amperecomputing.com, paulmck@kernel.org, akpm@linux-foundation.org, thuth@redhat.com, rostedt@goodmis.org, xiongwei.song@windriver.com, ardb@kernel.org, steven.price@arm.com, suzuki.poulose@arm.com, mark.rutland@arm.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, cl@os.amperecomputing.com References: <20241126085647.4993-1-shijie@os.amperecomputing.com> <20241126085647.4993-5-shijie@os.amperecomputing.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: <20241126085647.4993-5-shijie@os.amperecomputing.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/26/24 14:26, Huang Shijie wrote: > Put some fine-tuning tips in this file: > 1.) rodata=noalias > 2.) slab_strict_numa > 3.) CONFIG_SCHED_CLUSTER > > We can add more tips in future. > > Signed-off-by: Huang Shijie > --- > Documentation/arch/arm64/fine-tuning-tips.rst | 23 +++++++++++++++++++ > Documentation/arch/arm64/index.rst | 1 + > 2 files changed, 24 insertions(+) > create mode 100644 Documentation/arch/arm64/fine-tuning-tips.rst > > diff --git a/Documentation/arch/arm64/fine-tuning-tips.rst b/Documentation/arch/arm64/fine-tuning-tips.rst > new file mode 100644 > index 000000000000..70ef1cef92fb > --- /dev/null > +++ b/Documentation/arch/arm64/fine-tuning-tips.rst > @@ -0,0 +1,23 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +================ > +fine-tuning tips > +================ > + > +This file contains some fine-tuning tips for arm64 machines. > +These tips do not gurantee that you can get better performance, > +but you can try them with your workload. > + > +rodata=noalias > +---------------- > +It can provide us more block mappings and contiguous hits > +to map the linear region which minimizes the TLB footprint. > + > +slab_strict_numa > +---------------- > +In NUMA, it will provide the local memory allocation by SLUB. > + > +CONFIG_SCHED_CLUSTER > +---------------- > +Some arm64 machines have cpu core cluster, enable it may > +helps you get better performance. > diff --git a/Documentation/arch/arm64/index.rst b/Documentation/arch/arm64/index.rst > index 6a012c98bdcd..36d1ef09bd71 100644 > --- a/Documentation/arch/arm64/index.rst > +++ b/Documentation/arch/arm64/index.rst > @@ -16,6 +16,7 @@ ARM64 Architecture > cpu-feature-registers > cpu-hotplug > elf_hwcaps > + fine-tuning-tips > gcs > hugetlbpage > kdump Although the idea for such a file makes sense, to help system admins tune the kernel command line for required behaviour, I am concerned about the overall structure and scope for such a document. Should it contain tips regarding all the subsystems on the platform, till what extent these details should be described in there and then there are so many aspects for a required behaviour etc ? Besides maintaining such a document might also be very difficult as well given how implementations will change over time thus requiring different tuning etc. Hence kernel source might not be a place for such a document.