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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 9854DC433DB for ; Mon, 8 Mar 2021 22:31:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6387364FC8 for ; Mon, 8 Mar 2021 22:31:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230122AbhCHWbC (ORCPT ); Mon, 8 Mar 2021 17:31:02 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:2666 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231596AbhCHWaj (ORCPT ); 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"rjw@rjwysocki.net" , "vincent.guittot@linaro.org" , "bp@alien8.de" , "tglx@linutronix.de" , "mingo@redhat.com" , "lenb@kernel.org" , "dietmar.eggemann@arm.com" , "rostedt@goodmis.org" , "bsegall@google.com" , "mgorman@suse.de" , "msys.mizuma@gmail.com" , "valentin.schneider@arm.com" , "gregkh@linuxfoundation.org" , Jonathan Cameron , "juri.lelli@redhat.com" , "mark.rutland@arm.com" , "sudeep.holla@arm.com" , "aubrey.li@linux.intel.com" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "x86@kernel.org" , "xuwei (O)" , "Zengtao (B)" , "guodong.xu@linaro.org" , yangyicong , "Liguozhu (Kenneth)" , "linuxarm@openeuler.org" , "hpa@zytor.com" Subject: RE: [Linuxarm] Re: [RFC PATCH v4 3/3] scheduler: Add cluster scheduler level for x86 Thread-Topic: [Linuxarm] Re: [RFC PATCH v4 3/3] scheduler: Add cluster scheduler level for x86 Thread-Index: AQHXDu+AE3PNeTodl0O2xkA7PHQps6pv+jeAgAIZXACACJ6u4A== Date: Mon, 8 Mar 2021 22:30:33 +0000 Message-ID: <6d8940e227324c2c88474d9d0769c001@hisilicon.com> References: <20210301225940.16728-1-song.bao.hua@hisilicon.com> <20210301225940.16728-4-song.bao.hua@hisilicon.com> In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.126.203.229] Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 MIME-Version: 1.0 X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org DQoNCj4gLS0tLS1PcmlnaW5hbCBNZXNzYWdlLS0tLS0NCj4gRnJvbTogVGltIENoZW4gW21haWx0 bzp0aW0uYy5jaGVuQGxpbnV4LmludGVsLmNvbV0NCj4gU2VudDogVGh1cnNkYXksIE1hcmNoIDQs IDIwMjEgNzozNCBBTQ0KPiBUbzogUGV0ZXIgWmlqbHN0cmEgPHBldGVyekBpbmZyYWRlYWQub3Jn PjsgU29uZyBCYW8gSHVhIChCYXJyeSBTb25nKQ0KPiA8c29uZy5iYW8uaHVhQGhpc2lsaWNvbi5j b20+DQo+IENjOiBjYXRhbGluLm1hcmluYXNAYXJtLmNvbTsgd2lsbEBrZXJuZWwub3JnOyByandA cmp3eXNvY2tpLm5ldDsNCj4gdmluY2VudC5ndWl0dG90QGxpbmFyby5vcmc7IGJwQGFsaWVuOC5k 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22:30:35 +0000 Received: from dggemi761-chm.china.huawei.com ([10.9.49.202]) by dggemi761-chm.china.huawei.com ([10.9.49.202]) with mapi id 15.01.2106.013; Tue, 9 Mar 2021 06:30:34 +0800 From: "Song Bao Hua (Barry Song)" To: Tim Chen , Peter Zijlstra CC: "catalin.marinas@arm.com" , "will@kernel.org" , "rjw@rjwysocki.net" , "vincent.guittot@linaro.org" , "bp@alien8.de" , "tglx@linutronix.de" , "mingo@redhat.com" , "lenb@kernel.org" , "dietmar.eggemann@arm.com" , "rostedt@goodmis.org" , "bsegall@google.com" , "mgorman@suse.de" , "msys.mizuma@gmail.com" , "valentin.schneider@arm.com" , "gregkh@linuxfoundation.org" , Jonathan Cameron , "juri.lelli@redhat.com" , "mark.rutland@arm.com" , "sudeep.holla@arm.com" , "aubrey.li@linux.intel.com" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "x86@kernel.org" , "xuwei (O)" , "Zengtao (B)" , "guodong.xu@linaro.org" , yangyicong , "Liguozhu (Kenneth)" , "linuxarm@openeuler.org" , "hpa@zytor.com" Subject: RE: [Linuxarm] Re: [RFC PATCH v4 3/3] scheduler: Add cluster scheduler level for x86 Thread-Topic: [Linuxarm] Re: [RFC PATCH v4 3/3] scheduler: Add cluster scheduler level for x86 Thread-Index: AQHXDu+AE3PNeTodl0O2xkA7PHQps6pv+jeAgAIZXACACJ6u4A== Date: Mon, 8 Mar 2021 22:30:33 +0000 Message-ID: <6d8940e227324c2c88474d9d0769c001@hisilicon.com> References: <20210301225940.16728-1-song.bao.hua@hisilicon.com> <20210301225940.16728-4-song.bao.hua@hisilicon.com> In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.126.203.229] MIME-Version: 1.0 X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210308_223047_842032_5D3FF62D X-CRM114-Status: GOOD ( 19.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org > -----Original Message----- > From: Tim Chen [mailto:tim.c.chen@linux.intel.com] > Sent: Thursday, March 4, 2021 7:34 AM > To: Peter Zijlstra ; Song Bao Hua (Barry Song) > > Cc: catalin.marinas@arm.com; will@kernel.org; rjw@rjwysocki.net; > vincent.guittot@linaro.org; bp@alien8.de; tglx@linutronix.de; > mingo@redhat.com; lenb@kernel.org; dietmar.eggemann@arm.com; > rostedt@goodmis.org; bsegall@google.com; mgorman@suse.de; > msys.mizuma@gmail.com; valentin.schneider@arm.com; > gregkh@linuxfoundation.org; Jonathan Cameron ; > juri.lelli@redhat.com; mark.rutland@arm.com; sudeep.holla@arm.com; > aubrey.li@linux.intel.com; linux-arm-kernel@lists.infradead.org; > linux-kernel@vger.kernel.org; linux-acpi@vger.kernel.org; x86@kernel.org; > xuwei (O) ; Zengtao (B) ; > guodong.xu@linaro.org; yangyicong ; Liguozhu (Kenneth) > ; linuxarm@openeuler.org; hpa@zytor.com > Subject: [Linuxarm] Re: [RFC PATCH v4 3/3] scheduler: Add cluster scheduler > level for x86 > > > > On 3/2/21 2:30 AM, Peter Zijlstra wrote: > > On Tue, Mar 02, 2021 at 11:59:40AM +1300, Barry Song wrote: > >> From: Tim Chen > >> > >> There are x86 CPU architectures (e.g. Jacobsville) where L2 cahce > >> is shared among a cluster of cores instead of being exclusive > >> to one single core. > > > > Isn't that most atoms one way or another? Tremont seems to have it per 4 > > cores, but earlier it was per 2 cores. > > > > Yes, older Atoms have 2 cores sharing L2. I probably should > rephrase my comments to not leave the impression that sharing > L2 among cores is new for Atoms. > > Tremont based Atom CPUs increases the possible load imbalance more > with 4 cores per L2 instead of 2. And also with more overall cores on a die, > the > chance increases for packing running tasks on a few clusters while leaving > others empty on light/medium loaded systems. We did see > this effect on Jacobsville. > > So load balancing between the L2 clusters is more > useful on Tremont based Atom CPUs compared to the older Atoms. It seems sensible the more CPU we get in the cluster, the more we need the kernel to be aware of its existence. Tim, it is possible for you to bring up the cpu_cluster_mask and cluster_sibling for x86 so that the topology can be represented in sysfs and be used by scheduler? It seems your patch lacks this part. BTW, I wonder if x86 can do some improvement on your KMP_AFFINITY by leveraging the cluster topology level. https://software.intel.com/content/www/us/en/develop/documentation/cpp-compiler-developer-guide-and-reference/top/optimization-and-programming-guide/openmp-support/openmp-library-support/thread-affinity-interface-linux-and-windows.html KMP_AFFINITY has thread affinity modes like compact and scatter, it seems this "compact" and "scatter" can also use the cluster information as you see we are also struggling with the "compact" and "scatter" issues here in this patchset :-) Thanks Barry _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel