From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1125AC169C4 for ; Fri, 8 Feb 2019 17:40:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E01BA2146E for ; Fri, 8 Feb 2019 17:40:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727684AbfBHRkg (ORCPT ); Fri, 8 Feb 2019 12:40:36 -0500 Received: from foss.arm.com ([217.140.101.70]:55182 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727633AbfBHRkf (ORCPT ); Fri, 8 Feb 2019 12:40:35 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EE71780D; Fri, 8 Feb 2019 09:40:34 -0800 (PST) Received: from [10.1.196.62] (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D92523F719; Fri, 8 Feb 2019 09:40:32 -0800 (PST) Subject: Re: [patch V2 0/2] genirq, proc: Speedup /proc/stat interrupt statistics To: Thomas Gleixner , LKML Cc: Waiman Long , Matthew Wilcox , Andrew Morton , Alexey Dobriyan , Kees Cook , linux-fsdevel@vger.kernel.org, Davidlohr Bueso , Miklos Szeredi , Daniel Colascione , Dave Chinner , Randy Dunlap References: <20190208134802.218483159@linutronix.de> From: Marc Zyngier Openpgp: preference=signencrypt Autocrypt: addr=marc.zyngier@arm.com; prefer-encrypt=mutual; keydata= mQINBE6Jf0UBEADLCxpix34Ch3kQKA9SNlVQroj9aHAEzzl0+V8jrvT9a9GkK+FjBOIQz4KE g+3p+lqgJH4NfwPm9H5I5e3wa+Scz9wAqWLTT772Rqb6hf6kx0kKd0P2jGv79qXSmwru28vJ t9NNsmIhEYwS5eTfCbsZZDCnR31J6qxozsDHpCGLHlYym/VbC199Uq/pN5gH+5JHZyhyZiNW ozUCjMqC4eNW42nYVKZQfbj/k4W9xFfudFaFEhAf/Vb1r6F05eBP1uopuzNkAN7vqS8XcgQH qXI357YC4ToCbmqLue4HK9+2mtf7MTdHZYGZ939OfTlOGuxFW+bhtPQzsHiW7eNe0ew0+LaL 3wdNzT5abPBscqXWVGsZWCAzBmrZato+Pd2bSCDPLInZV0j+rjt7MWiSxEAEowue3IcZA++7 ifTDIscQdpeKT8hcL+9eHLgoSDH62SlubO/y8bB1hV8JjLW/jQpLnae0oz25h39ij4ijcp8N t5slf5DNRi1NLz5+iaaLg4gaM3ywVK2VEKdBTg+JTg3dfrb3DH7ctTQquyKun9IVY8AsxMc6 lxl4HxrpLX7HgF10685GG5fFla7R1RUnW5svgQhz6YVU33yJjk5lIIrrxKI/wLlhn066mtu1 DoD9TEAjwOmpa6ofV6rHeBPehUwMZEsLqlKfLsl0PpsJwov8TQARAQABtCNNYXJjIFp5bmdp ZXIgPG1hcmMuenluZ2llckBhcm0uY29tPokCOwQTAQIAJQIbAwYLCQgHAwIGFQgCCQoLBBYC AwECHgECF4AFAk6NvYYCGQEACgkQI9DQutE9ekObww/+NcUATWXOcnoPflpYG43GZ0XjQLng LQFjBZL+CJV5+1XMDfz4ATH37cR+8gMO1UwmWPv5tOMKLHhw6uLxGG4upPAm0qxjRA/SE3LC 22kBjWiSMrkQgv5FDcwdhAcj8A+gKgcXBeyXsGBXLjo5UQOGvPTQXcqNXB9A3ZZN9vS6QUYN TXFjnUnzCJd+PVI/4jORz9EUVw1q/+kZgmA8/GhfPH3xNetTGLyJCJcQ86acom2liLZZX4+1 6Hda2x3hxpoQo7pTu+XA2YC4XyUstNDYIsE4F4NVHGi88a3N8yWE+Z7cBI2HjGvpfNxZnmKX 6bws6RQ4LHDPhy0yzWFowJXGTqM/e79c1UeqOVxKGFF3VhJJu1nMlh+5hnW4glXOoy/WmDEM UMbl9KbJUfo+GgIQGMp8mwgW0vK4HrSmevlDeMcrLdfbbFbcZLNeFFBn6KqxFZaTd+LpylIH bOPN6fy1Dxf7UZscogYw5Pt0JscgpciuO3DAZo3eXz6ffj2NrWchnbj+SpPBiH4srfFmHY+Y LBemIIOmSqIsjoSRjNEZeEObkshDVG5NncJzbAQY+V3Q3yo9og/8ZiaulVWDbcpKyUpzt7pv cdnY3baDE8ate/cymFP5jGJK++QCeA6u6JzBp7HnKbngqWa6g8qDSjPXBPCLmmRWbc5j0lvA 6ilrF8m5Ag0ETol/RQEQAM/2pdLYCWmf3rtIiP8Wj5NwyjSL6/UrChXtoX9wlY8a4h3EX6E3 64snIJVMLbyr4bwdmPKULlny7T/R8dx/mCOWu/DztrVNQiXWOTKJnd/2iQblBT+W5W8ep/nS w3qUIckKwKdplQtzSKeE+PJ+GMS+DoNDDkcrVjUnsoCEr0aK3cO6g5hLGu8IBbC1CJYSpple VVb/sADnWF3SfUvJ/l4K8Uk4B4+X90KpA7U9MhvDTCy5mJGaTsFqDLpnqp/yqaT2P7kyMG2E w+eqtVIqwwweZA0S+tuqput5xdNAcsj2PugVx9tlw/LJo39nh8NrMxAhv5aQ+JJ2I8UTiHLX QvoC0Yc/jZX/JRB5r4x4IhK34Mv5TiH/gFfZbwxd287Y1jOaD9lhnke1SX5MXF7eCT3cgyB+ hgSu42w+2xYl3+rzIhQqxXhaP232t/b3ilJO00ZZ19d4KICGcakeiL6ZBtD8TrtkRiewI3v0 o8rUBWtjcDRgg3tWx/PcJvZnw1twbmRdaNvsvnlapD2Y9Js3woRLIjSAGOijwzFXSJyC2HU1 AAuR9uo4/QkeIrQVHIxP7TJZdJ9sGEWdeGPzzPlKLHwIX2HzfbdtPejPSXm5LJ026qdtJHgz BAb3NygZG6BH6EC1NPDQ6O53EXorXS1tsSAgp5ZDSFEBklpRVT3E0NrDABEBAAGJAh8EGAEC AAkFAk6Jf0UCGwwACgkQI9DQutE9ekMLBQ//U+Mt9DtFpzMCIHFPE9nNlsCm75j22lNiw6mX mx3cUA3pl+uRGQr/zQC5inQNtjFUmwGkHqrAw+SmG5gsgnM4pSdYvraWaCWOZCQCx1lpaCOl MotrNcwMJTJLQGc4BjJyOeSH59HQDitKfKMu/yjRhzT8CXhys6R0kYMrEN0tbe1cFOJkxSbV 0GgRTDF4PKyLT+RncoKxQe8lGxuk5614aRpBQa0LPafkirwqkUtxsPnarkPUEfkBlnIhAR8L kmneYLu0AvbWjfJCUH7qfpyS/FRrQCoBq9QIEcf2v1f0AIpA27f9KCEv5MZSHXGCdNcbjKw1 39YxYZhmXaHFKDSZIC29YhQJeXWlfDEDq6nIhvurZy3mSh2OMQgaIoFexPCsBBOclH8QUtMk a3jW/qYyrV+qUq9Wf3SKPrXf7B3xB332jFCETbyZQXqmowV+2b3rJFRWn5hK5B+xwvuxKyGq qDOGjof2dKl2zBIxbFgOclV7wqCVkhxSJi/QaOj2zBqSNPXga5DWtX3ekRnJLa1+ijXxmdjz hApihi08gwvP5G9fNGKQyRETePEtEAWt0b7dOqMzYBYGRVr7uS4uT6WP7fzOwAJC4lU7ZYWZ yVshCa0IvTtp1085RtT3qhh9mobkcZ+7cQOY+Tx2RGXS9WeOh2jZjdoWUv6CevXNQyOUXMM= Organization: ARM Ltd Message-ID: <0a0ad274-83fb-8310-a306-68aa65eeef63@arm.com> Date: Fri, 8 Feb 2019 17:40:30 +0000 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190208134802.218483159@linutronix.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 08/02/2019 13:48, Thomas Gleixner wrote: > Waiman reported that on large systems with a large amount of interrupts the > readout of /proc/stat takes a long time to sum up the interrupt > statistics. In principle this is not a problem. but for unknown reasons > some enterprise quality software reads /proc/stat with a high frequency. > > The reason for this is that interrupt statistics are accounted per cpu. So > the /proc/stat logic has to sum up the interrupt stats for each interrupt. > > The following series addresses this by making the interrupt statitics code > in the core generate the sum directly and by making the loop in the > /proc/stat read function smarter. > > V1 -> V2: Address review feedback: undo struct layout changes, make > variables unsigned and add test results to the changelog. > > Thanks, > > tglx > > 8<---------------- > fs/proc/stat.c | 29 ++++++++++++++++++++++++++--- > include/linux/irqdesc.h | 1 + > kernel/irq/chip.c | 12 ++++++++++-- > kernel/irq/internals.h | 8 +++++++- > kernel/irq/irqdesc.c | 7 ++++++- > 5 files changed, 50 insertions(+), 7 deletions(-) > Reviewed-by: Marc Zyngier Thanks, M. -- Jazz is not dead. It just smells funny...