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=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 DF942C63793 for ; Thu, 22 Jul 2021 05:23:31 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 3413461264 for ; Thu, 22 Jul 2021 05:23:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3413461264 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:44402 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m6RBC-0004nA-2v for qemu-devel@archiver.kernel.org; Thu, 22 Jul 2021 01:23:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34706) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m6RAK-00046G-HS for qemu-devel@nongnu.org; Thu, 22 Jul 2021 01:22:37 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:2441) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m6RAH-0001JK-AW for qemu-devel@nongnu.org; Thu, 22 Jul 2021 01:22:36 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4GVgjL6V99zZrZw; Thu, 22 Jul 2021 13:19:02 +0800 (CST) Received: from dggpemm500023.china.huawei.com (7.185.36.83) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 22 Jul 2021 13:22:26 +0800 Received: from [10.174.187.128] (10.174.187.128) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Thu, 22 Jul 2021 13:22:25 +0800 Subject: Re: [PATCH for-6.2 v2 07/11] machine: Prefer cores over sockets in smp parsing since 6.2 To: David Gibson References: <20210719032043.25416-1-wangyanan55@huawei.com> <20210719032043.25416-8-wangyanan55@huawei.com> From: "wangyanan (Y)" Message-ID: <947f142e-cf59-c7b4-be10-365e94cad162@huawei.com> Date: Thu, 22 Jul 2021 13:22:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.174.187.128] X-ClientProxiedBy: dggeme716-chm.china.huawei.com (10.1.199.112) To dggpemm500023.china.huawei.com (7.185.36.83) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=45.249.212.187; envelope-from=wangyanan55@huawei.com; helo=szxga01-in.huawei.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.117, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Andrew Jones , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Eduardo Habkost , "Michael S . Tsirkin" , wanghaibin.wang@huawei.com, Richard Henderson , qemu-devel@nongnu.org, Greg Kurz , Halil Pasic , yuzenghui@huawei.com, Igor Mammedov , Thomas Huth , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2021/7/19 11:40, David Gibson wrote: > On Mon, Jul 19, 2021 at 11:20:39AM +0800, Yanan Wang wrote: >> In the real SMP hardware topology world, it's much more likely that >> we have high cores-per-socket counts and few sockets totally. While >> the current preference of sockets over cores in smp parsing results >> in a virtual cpu topology with low cores-per-sockets counts and a >> large number of sockets, which is just contrary to the real world. >> >> Given that it is better to make the virtual cpu topology be more >> reflective of the real world and also for the sake of compatibility, >> we start to prefer cores over sockets over threads in smp parsing >> since machine type 6.2 for different arches. >> >> In this patch, a boolean "smp_prefer_sockets" is added, and we only >> enable the old preference on older machines and enable the new one >> since type 6.2 for all arches by using the machine compat mechanism. >> >> Suggested-by: Daniel P. Berrange >> Signed-off-by: Yanan Wang > ppc parts > > Acked-by: David Gibson > > Note that for the pseries machine types, being paravirtual, there is > essentially no guest visible difference between "cores" and "sockets. I see. When the difference start to make some sense for the pseries guest, then I think high-count cores may also be preferred and we will already have the preference of cores at that time because of today's work. Thanks, Yanan . >> --- >> hw/arm/virt.c | 1 + >> hw/core/machine.c | 59 +++++++++++++++++++++++++++++--------- >> hw/i386/pc_piix.c | 1 + >> hw/i386/pc_q35.c | 1 + >> hw/ppc/spapr.c | 1 + >> hw/s390x/s390-virtio-ccw.c | 1 + >> include/hw/boards.h | 1 + >> qemu-options.hx | 4 ++- >> 8 files changed, 55 insertions(+), 14 deletions(-) >> >> diff --git a/hw/arm/virt.c b/hw/arm/virt.c >> index 01165f7f53..7babea40dc 100644 >> --- a/hw/arm/virt.c >> +++ b/hw/arm/virt.c >> @@ -2797,6 +2797,7 @@ static void virt_machine_6_1_options(MachineClass *mc) >> { >> virt_machine_6_2_options(mc); >> compat_props_add(mc->compat_props, hw_compat_6_1, hw_compat_6_1_len); >> + mc->smp_prefer_sockets = true; >> } >> DEFINE_VIRT_MACHINE(6, 1) >> >> diff --git a/hw/core/machine.c b/hw/core/machine.c >> index 63439c4a6d..c074425015 100644 >> --- a/hw/core/machine.c >> +++ b/hw/core/machine.c >> @@ -744,6 +744,22 @@ void machine_set_cpu_numa_node(MachineState *machine, >> } >> } >> >> +/* >> + * smp_parse - Generic function used to parse the given SMP configuration >> + * >> + * The topology parameters must be specified equal to or great than one >> + * or just omitted, explicit configuration like "cpus=0" is not allowed. >> + * The omitted parameters will be calculated based on the provided ones. >> + * >> + * maxcpus will default to the value of cpus if omitted and will be used >> + * to compute the missing sockets/cores/threads. cpus will be calculated >> + * from the computed parametrs if omitted. >> + * >> + * In calculation of omitted arch-netural sockets/cores/threads, we prefer >> + * sockets over cores over threads before 6.2, while prefer cores over >> + * sockets over threads since 6.2 on. The arch-specific dies will directly >> + * default to 1 if omitted. >> + */ >> static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp) >> { >> MachineClass *mc = MACHINE_GET_CLASS(ms); >> @@ -772,19 +788,36 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp) >> >> maxcpus = maxcpus > 0 ? maxcpus : cpus; >> >> - /* compute missing values, prefer sockets over cores over threads */ >> - if (sockets == 0) { >> - cores = cores > 0 ? cores : 1; >> - threads = threads > 0 ? threads : 1; >> - sockets = maxcpus / (dies * cores * threads); >> - sockets = sockets > 0 ? sockets : 1; >> - } else if (cores == 0) { >> - threads = threads > 0 ? threads : 1; >> - cores = maxcpus / (sockets * dies * threads); >> - cores = cores > 0 ? cores : 1; >> - } else if (threads == 0) { >> - threads = maxcpus / (sockets * dies * cores); >> - threads = threads > 0 ? threads : 1; >> + /* prefer sockets over cores over threads before 6.2 */ >> + if (mc->smp_prefer_sockets) { >> + if (sockets == 0) { >> + cores = cores > 0 ? cores : 1; >> + threads = threads > 0 ? threads : 1; >> + sockets = maxcpus / (dies * cores * threads); >> + sockets = sockets > 0 ? sockets : 1; >> + } else if (cores == 0) { >> + threads = threads > 0 ? threads : 1; >> + cores = maxcpus / (sockets * dies * threads); >> + cores = cores > 0 ? cores : 1; >> + } else if (threads == 0) { >> + threads = maxcpus / (sockets * dies * cores); >> + threads = threads > 0 ? threads : 1; >> + } >> + /* prefer cores over sockets over threads since 6.2 */ >> + } else { >> + if (cores == 0) { >> + sockets = sockets > 0 ? sockets : 1; >> + threads = threads > 0 ? threads : 1; >> + cores = maxcpus / (sockets * dies * threads); >> + cores = cores > 0 ? cores : 1; >> + } else if (sockets == 0) { >> + threads = threads > 0 ? threads : 1; >> + sockets = maxcpus / (dies * cores * threads); >> + sockets = sockets > 0 ? sockets : 1; >> + } else if (threads == 0) { >> + threads = maxcpus / (sockets * dies * cores); >> + threads = threads > 0 ? threads : 1; >> + } >> } >> >> /* use the computed parameters to calculate the omitted cpus */ >> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c >> index fd5c2277f2..9b811fc6ca 100644 >> --- a/hw/i386/pc_piix.c >> +++ b/hw/i386/pc_piix.c >> @@ -432,6 +432,7 @@ static void pc_i440fx_6_1_machine_options(MachineClass *m) >> m->is_default = false; >> compat_props_add(m->compat_props, hw_compat_6_1, hw_compat_6_1_len); >> compat_props_add(m->compat_props, pc_compat_6_1, pc_compat_6_1_len); >> + m->smp_prefer_sockets = true; >> } >> >> DEFINE_I440FX_MACHINE(v6_1, "pc-i440fx-6.1", NULL, >> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c >> index b45903b15e..88efb7fde4 100644 >> --- a/hw/i386/pc_q35.c >> +++ b/hw/i386/pc_q35.c >> @@ -372,6 +372,7 @@ static void pc_q35_6_1_machine_options(MachineClass *m) >> m->alias = NULL; >> compat_props_add(m->compat_props, hw_compat_6_1, hw_compat_6_1_len); >> compat_props_add(m->compat_props, pc_compat_6_1, pc_compat_6_1_len); >> + m->smp_prefer_sockets = true; >> } >> >> DEFINE_Q35_MACHINE(v6_1, "pc-q35-6.1", NULL, >> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c >> index d39fd4e644..a481fade51 100644 >> --- a/hw/ppc/spapr.c >> +++ b/hw/ppc/spapr.c >> @@ -4702,6 +4702,7 @@ static void spapr_machine_6_1_class_options(MachineClass *mc) >> { >> spapr_machine_6_2_class_options(mc); >> compat_props_add(mc->compat_props, hw_compat_6_1, hw_compat_6_1_len); >> + mc->smp_prefer_sockets = true; >> } >> >> DEFINE_SPAPR_MACHINE(6_1, "6.1", false); >> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c >> index 4d25278cf2..b40e647883 100644 >> --- a/hw/s390x/s390-virtio-ccw.c >> +++ b/hw/s390x/s390-virtio-ccw.c >> @@ -809,6 +809,7 @@ static void ccw_machine_6_1_class_options(MachineClass *mc) >> { >> ccw_machine_6_2_class_options(mc); >> compat_props_add(mc->compat_props, hw_compat_6_1, hw_compat_6_1_len); >> + mc->smp_prefer_sockets = true; >> } >> DEFINE_CCW_MACHINE(6_1, "6.1", false); >> >> diff --git a/include/hw/boards.h b/include/hw/boards.h >> index 2832f0f8aa..8df885c9d2 100644 >> --- a/include/hw/boards.h >> +++ b/include/hw/boards.h >> @@ -247,6 +247,7 @@ struct MachineClass { >> bool nvdimm_supported; >> bool numa_mem_supported; >> bool smp_dies_supported; >> + bool smp_prefer_sockets; >> bool auto_enable_numa; >> const char *default_ram_id; >> >> diff --git a/qemu-options.hx b/qemu-options.hx >> index 0c9ddc0274..6ef57e838c 100644 >> --- a/qemu-options.hx >> +++ b/qemu-options.hx >> @@ -227,7 +227,9 @@ SRST >> from those which are given. Historically preference was given to the >> coarsest topology parameters when computing missing values (ie sockets >> preferred over cores, which were preferred over threads), however, this >> - behaviour is considered liable to change. >> + behaviour is considered liable to change. The historical preference of >> + sockets over cores over threads works before 6.2, and a new preference >> + of cores over sockets over threads starts to work since 6.2 on. >> ERST >> >> DEF("numa", HAS_ARG, QEMU_OPTION_numa,