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,DKIM_INVALID, DKIM_SIGNED,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 56AEBC433DF for ; Fri, 31 Jul 2020 11:34:33 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0381422B40 for ; Fri, 31 Jul 2020 11:34:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="j9+9K8UJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0381422B40 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4BJ4tv16sbzDqg4 for ; Fri, 31 Jul 2020 21:34:31 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4BJ4qB1NTzzDqNT for ; Fri, 31 Jul 2020 21:31:18 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=j9+9K8UJ; dkim-atps=neutral Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4BJ4q64xhRz9sTM; Fri, 31 Jul 2020 21:31:14 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1596195074; bh=sEHXx5GmyjktVn/nBfOnSByax6uQ2hzqiMlXONEK7HE=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=j9+9K8UJvsoOJPGC52wJJ8GBd4ZXcwaQdD4S6QXKl+SpP33BYz+OKTOgncwB/iZtu 0LNW01IfHgVvOx+w8gEc6alSQjNJ5V5TxgzBAznm57vQ2SkKu0SdfqxriJ2r6l/JV4 C2a0u0/P78Yn3f9bp7/4RhsG52eLOQDoizTdx5BoZCHMFMnYtjm4zlMS0KLiyi11tn Fsqcr3rpPQE1YFPQoTrFzcAyG/y5MJ9G25Zn0KyOVtXuMuCtmi9pOxTPWWqaDvosMo sipNLZxyMiDxo4S6hkVJai1hutnkrmhOsz6PK2WIQU/IOjYcMkB8+ZFmkYPoWQoR5v oW5m3k+uPQs9A== From: Michael Ellerman To: Srikar Dronamraju Subject: Re: [PATCH v4 07/10] Powerpc/numa: Detect support for coregroup In-Reply-To: <20200731091859.GG14603@linux.vnet.ibm.com> References: <20200727053230.19753-1-srikar@linux.vnet.ibm.com> <20200727053230.19753-8-srikar@linux.vnet.ibm.com> <8736585djw.fsf@mpe.ellerman.id.au> <20200731091859.GG14603@linux.vnet.ibm.com> Date: Fri, 31 Jul 2020 21:31:13 +1000 Message-ID: <87r1sr53b2.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nathan Lynch , Gautham R Shenoy , Michael Neuling , Peter Zijlstra , Jordan Niethe , LKML , Nicholas Piggin , Valentin Schneider , Oliver O'Halloran , linuxppc-dev , Ingo Molnar Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Srikar Dronamraju writes: > * Michael Ellerman [2020-07-31 17:49:55]: > >> Srikar Dronamraju writes: >> > Add support for grouping cores based on the device-tree classification. >> > - The last domain in the associativity domains always refers to the >> > core. >> > - If primary reference domain happens to be the penultimate domain in >> > the associativity domains device-tree property, then there are no >> > coregroups. However if its not a penultimate domain, then there are >> > coregroups. There can be more than one coregroup. For now we would be >> > interested in the last or the smallest coregroups. >> >> This still doesn't tell me what a coregroup actually represents. >> >> I get that it's a grouping of cores, and that the device tree specifies >> it for us, but grouping based on what? > > We have just abstracted the fact that we are creating a sub-group of cores > within a DIE. We are limiting to one sub-group per core. However this would > allow the firmware the flexibility to vary the grouping. Once the firmware > starts using this group, we could add more code to detect the type of > grouping and adjust the sd domain flags accordingly. OK. That's good info to have in the change log. >> I think the answer is we aren't being told by firmware, it's just a >> grouping based on some opaque performance characteristic and we just >> have to take that as given. >> > > This is partially true. At this time, we dont have firmwares that can > exploit this code. Once the firmwares start using this grouping, we could > add more code to align the grouping to the scheduler topology. > >> But please explain that clearly in the change log and the code comments. >> > > Okay, I will do the needful. Thanks. cheers