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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A1966E7718B for ; Mon, 23 Dec 2024 16:34:57 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4YH3XJ0PD6z2yZN; Tue, 24 Dec 2024 03:34:56 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=185.176.79.56 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1734971696; cv=none; b=YAsttuy49yp3cc96FN9C/qlsIOqcTKzkvKVHxVQXno33GbelHfOgdjIeDJHXVfb6QxjN1SY8D6+tph+MSHL0BkBH6kfgjUAfO5QQmJePfHvicb7tSbB7+0jrFGApg5F6+JawekB0D1LhHh+cKTxwhgqAAor0U0sUFL0LpDE60L7gBXfrcw0WODK4Zij5S7iLM4MpvXU6dbwaBF7p1mObceIzHD9S59heZM0O6TIhjXqpgISAvL1UEDX0OHoL5e22bl4c/TtUfQnukqc/Mop59WnBoP8XfuBKaSdZtLooe79O9Nx/eQwqWFaxjaF2R7kxcoR8Va+okvsuTEJH3Cd0nQ== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1734971696; c=relaxed/relaxed; bh=iVYJ8ouxXEJ32vKRS7dpUfPVWa7BlVRd+beBSZ+Z43o=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=juk6mRxpIuND0ZMU/GyruZYojxjj5e6REU43nUXhZlSxynJqNMZzjMUJL1yAnWXDXCKugiSTkb5vBgRONeoivn/990dXZMFmulMF6U9fx97/4OGQly1ewAif88E0RS39dBe2DUXiVW1a1ZdVRyPRz5OURrF2Icv98RVUKozh1oEBJWfDUXSpVxywANrZV9EM0/cjB+owZED4NT4iAdA8SdvsY2JKti60jYyckaMNI7MP9ixgHwZjpUoEdrABSeUmqVpOLCXiQ5Y2RuJp1k8sN9a7t+9t0PaSzaxOkxdHNqzjVEkPLWMYTDZLA9U7xCziiocdyHzATi5jGrq69JAy8w== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass (client-ip=185.176.79.56; helo=frasgout.his.huawei.com; envelope-from=jonathan.cameron@huawei.com; receiver=lists.ozlabs.org) smtp.mailfrom=huawei.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=huawei.com (client-ip=185.176.79.56; helo=frasgout.his.huawei.com; envelope-from=jonathan.cameron@huawei.com; receiver=lists.ozlabs.org) Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4YH3XG6TZXz2xxw for ; Tue, 24 Dec 2024 03:34:54 +1100 (AEDT) Received: from mail.maildlp.com (unknown [172.18.186.231]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4YH3Wv2jWzz6K6jC; Tue, 24 Dec 2024 00:34:35 +0800 (CST) Received: from frapeml500008.china.huawei.com (unknown [7.182.85.71]) by mail.maildlp.com (Postfix) with ESMTPS id 508A2140517; Tue, 24 Dec 2024 00:34:52 +0800 (CST) Received: from localhost (10.47.75.118) by frapeml500008.china.huawei.com (7.182.85.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Mon, 23 Dec 2024 17:34:50 +0100 Date: Mon, 23 Dec 2024 16:34:48 +0000 From: Jonathan Cameron To: Yicong Yang CC: , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v10 1/4] cpu/SMT: Provide a default topology_is_primary_thread() Message-ID: <20241223163448.00004354@huawei.com> In-Reply-To: References: <20241220075313.51502-1-yangyicong@huawei.com> <20241220075313.51502-2-yangyicong@huawei.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.75.118] X-ClientProxiedBy: lhrpeml500004.china.huawei.com (7.191.163.9) To frapeml500008.china.huawei.com (7.182.85.71) On Fri, 20 Dec 2024 15:59:27 +0800 Yicong Yang wrote: > On 2024/12/20 15:53, Yicong Yang wrote: > > From: Yicong Yang > > > > Currently if architectures want to support HOTPLUG_SMT they need to > > provide a topology_is_primary_thread() telling the framework which > > thread in the SMT cannot offline. However arm64 doesn't have a > > restriction on which thread in the SMT cannot offline, a simplest > > choice is that just make 1st thread as the "primary" thread. So > > just make this as the default implementation in the framework and > > let architectures like x86 that have special primary thread to > > override this function (which they've already done). > > > > There's no need to provide a stub function if !CONFIG_SMP or > > !CONFIG_HOTPLUG_SMP. In such case the testing CPU is already > > the 1st CPU in the SMT so it's always the primary thread. > > > > Signed-off-by: Yicong Yang > > --- > > As questioned in v9 [1] whether this works on architectures not using > > CONFIG_GENERIC_ARCH_TOPOLOGY, hacked on LoongArch VM and this also works. > > Architectures should use this on their own situation. > > [1] https://lore.kernel.org/linux-arm-kernel/427bd639-33c3-47e4-9e83-68c428eb1a7d@arm.com/ > > > > [root@localhost smt]# uname -m > > loongarch64 > > [root@localhost smt]# pwd > > /sys/devices/system/cpu/smt > > [root@localhost smt]# cat ../possible > > 0-3 > > [root@localhost smt]# cat ../online > > 0-3 > > [root@localhost smt]# cat control > > on > > [root@localhost smt]# echo off > control > > [root@localhost smt]# cat control > > off > > [root@localhost smt]# cat ../online > > 0,2 > > [root@localhost smt]# echo on > control > > [root@localhost smt]# cat control > > on > > [root@localhost smt]# cat ../online > > 0-3 > > Tested with below code using the topology_is_primary_thread() introduced > in this patch. Tested on an ACPI-based QEMU VM emulating SMT2. Nice bit of testing. Given it all seems fine. FWIW Reviewed-by: Jonathan Cameron (for original patch, not the longarch one!) > > Subject: [PATCH] LoongArch: Support HOTPLUG_SMT on ACPI-based system > > Support HOTPLUG_SMT on ACPI-based system using generic > topology_is_primary_thread(). > > Signed-off-by: Yicong Yang > --- > arch/loongarch/Kconfig | 1 + > arch/loongarch/kernel/acpi.c | 26 ++++++++++++++++++++++++-- > 2 files changed, 25 insertions(+), 2 deletions(-) > > diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig > index dae3a9104ca6..bed1b0640b97 100644 > --- a/arch/loongarch/Kconfig > +++ b/arch/loongarch/Kconfig > @@ -172,6 +172,7 @@ config LOONGARCH > select HAVE_SYSCALL_TRACEPOINTS > select HAVE_TIF_NOHZ > select HAVE_VIRT_CPU_ACCOUNTING_GEN if !SMP > + select HOTPLUG_SMT if HOTPLUG_CPU > select IRQ_FORCED_THREADING > select IRQ_LOONGARCH_CPU > select LOCK_MM_AND_FIND_VMA > diff --git a/arch/loongarch/kernel/acpi.c b/arch/loongarch/kernel/acpi.c > index 382a09a7152c..e642b0de57e7 100644 > --- a/arch/loongarch/kernel/acpi.c > +++ b/arch/loongarch/kernel/acpi.c > @@ -15,9 +15,11 @@ > #include > #include > #include > +#include > #include > #include > #include > +#include > > int acpi_disabled; > EXPORT_SYMBOL(acpi_disabled); > @@ -175,8 +177,12 @@ int pptt_enabled; > > int __init parse_acpi_topology(void) > { > + int thread_num, max_smt_thread_num = 1; > + struct xarray core_threads; > int cpu, topology_id; > + void *entry; > > + xa_init(&core_threads); > for_each_possible_cpu(cpu) { > topology_id = find_acpi_cpu_topology(cpu, 0); > if (topology_id < 0) { > @@ -184,19 +190,35 @@ int __init parse_acpi_topology(void) > return -ENOENT; > } > > - if (acpi_pptt_cpu_is_thread(cpu) <= 0) > + if (acpi_pptt_cpu_is_thread(cpu) <= 0) { > cpu_data[cpu].core = topology_id; > - else { > + } else { > topology_id = find_acpi_cpu_topology(cpu, 1); > if (topology_id < 0) > return -ENOENT; > > cpu_data[cpu].core = topology_id; > + > + entry = xa_load(&core_threads, topology_id); > + if (!entry) { > + xa_store(&core_threads, topology_id, > + xa_mk_value(1), GFP_KERNEL); > + } else { > + thread_num = xa_to_value(entry); > + thread_num++; > + xa_store(&core_threads, topology_id, > + xa_mk_value(thread_num), GFP_KERNEL); > + > + if (thread_num > max_smt_thread_num) > + max_smt_thread_num = thread_num; > + } > } > } > > pptt_enabled = 1; > > + cpu_smt_set_num_threads(max_smt_thread_num, max_smt_thread_num); > + xa_destroy(&core_threads); > return 0; > } >