Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751480AbdLMXJ5 (ORCPT ); Wed, 13 Dec 2017 18:09:57 -0500 Received: from mail-oi0-f68.google.com ([209.85.218.68]:38413 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751011AbdLMXJz (ORCPT ); Wed, 13 Dec 2017 18:09:55 -0500 X-Google-Smtp-Source: ACJfBovknjPO7+PWPhUWR210vJYhrQnNKD9VUFvTjJRuXUgajoptpCf550SPl5Xi/CUGsjluPuw7gQ54pEAp9B1AVhU= MIME-Version: 1.0 In-Reply-To: <6aca3fa0-9099-f283-ae16-0c48aa00d00d@arm.com> References: <20171201222330.18863-1-jeremy.linton@arm.com> <20171201222330.18863-7-jeremy.linton@arm.com> <9009154.M66RGdQJXA@aspire.rjw.lan> <20171213173851.GA4060@red-moon> <6aca3fa0-9099-f283-ae16-0c48aa00d00d@arm.com> From: "Rafael J. Wysocki" Date: Thu, 14 Dec 2017 00:09:54 +0100 X-Google-Sender-Auth: hlxroFBuV1uThULE7UHy5D6k1BU Message-ID: Subject: Re: [PATCH v5 6/9] ACPI/PPTT: Add topology parsing code To: Jeremy Linton Cc: "Rafael J. Wysocki" , Lorenzo Pieralisi , "Rafael J. Wysocki" , ACPI Devel Maling List , "linux-arm-kernel@lists.infradead.org" , Sudeep Holla , Hanjun Guo , Will Deacon , Catalin Marinas , Greg Kroah-Hartman , Viresh Kumar , Mark Rutland , Linux Kernel Mailing List , Linux PM , jhugo@codeaurora.org, wangxiongfeng2@huawei.com, Jonathan.Zhang@cavium.com, Al Stone , Jayachandran.Nair@cavium.com, austinwc@codeaurora.org, Len Brown Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2193 Lines: 66 On Thu, Dec 14, 2017 at 12:06 AM, Jeremy Linton wrote: > Hi, > > > On 12/13/2017 04:28 PM, Rafael J. Wysocki wrote: >> >> On Wed, Dec 13, 2017 at 6:38 PM, Lorenzo Pieralisi >> wrote: >>> >>> On Tue, Dec 12, 2017 at 10:13:08AM -0600, Jeremy Linton wrote: >>>> >>>> Hi, >>>> >>>> First, thanks for taking a look at this. >>>> >>>> On 12/11/2017 07:12 PM, Rafael J. Wysocki wrote: >>>>> >>>>> On Friday, December 1, 2017 11:23:27 PM CET Jeremy Linton wrote: >>>>>> >>>>>> The PPTT can be used to determine the groupings of CPU's at >>>>>> given levels in the system. Lets add a few routines to the PPTT >>>>>> parsing code to return a unique id for each unique level in the >>>>>> processor hierarchy. This can then be matched to build >>>>>> thread/core/cluster/die/package/etc mappings for each processing >>>>>> element in the system. >>>>>> >>>>>> Signed-off-by: Jeremy Linton >>>>> >>>>> >>>>> Why can't this be folded into patch [2/9]? >>>> >>>> >>>> It can, and I will be happy squash it. >>>> >>>> It was requested that the topology portion of the parser be split >>>> out back in v3. >>>> >>>> https://www.spinics.net/lists/linux-acpi/msg78487.html >>> >>> >>> I asked to split cache/topology since I am not familiar with cache >>> code and Sudeep - who looks after the cache code - won't be able >>> to review this series in time for v4.16. >> >> >> OK, so why do we need it in 4.16? > > > I think its more case of as soon as possible. That is because there are > machines where the topology is completely incorrect due to assumptions the > kernel makes based on registers that aren't defined for that purpose (say > describing which cores are in a physical socket, or LLC's attached to > interconnects or memory controllers). > > This incorrect topology information is reported to things like the kernel > scheduler, which then makes poor scheduling decisions resulting in > sub-optimal system performance. > > This patchset (and ACPI 6.2) clears up a lot of those problems. As long as the ACPI tables are as expected that is, I suppose? Anyway, fair enough, but I don't want to rush it in. Thanks, Rafael