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[31.30.174.132]) by smtp.gmail.com with ESMTPSA id j20sm1642810ejc.110.2021.04.28.03.23.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Apr 2021 03:23:55 -0700 (PDT) Date: Wed, 28 Apr 2021 12:23:53 +0200 From: Andrew Jones To: Yanan Wang Subject: Re: [RFC PATCH v2 1/4] vl.c: Add -smp, clusters=* command line support for ARM cpu Message-ID: <20210428102353.cfjvzss56c4zwb4y@gator> References: <20210413083147.34236-1-wangyanan55@huawei.com> <20210413083147.34236-2-wangyanan55@huawei.com> MIME-Version: 1.0 In-Reply-To: <20210413083147.34236-2-wangyanan55@huawei.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=drjones@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=drjones@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.218, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: Barry Song , Peter Maydell , "Michael S . Tsirkin" , wanghaibin.wang@huawei.com, qemu-devel@nongnu.org, yangyicong@huawei.com, Shannon Zhao , qemu-arm@nongnu.org, Alistair Francis , prime.zeng@hisilicon.com, Igor Mammedov , yuzenghui@huawei.com, Paolo Bonzini , zhukeqian1@huawei.com, Jiajie Li , David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Apr 13, 2021 at 04:31:44PM +0800, Yanan Wang wrote: > A cluster means a group of cores that share some resources (e.g. cache) > among them under the LLC. For example, ARM64 server chip Kunpeng 920 has > 6 or 8 clusters in each NUMA, and each cluster has 4 cores. All clusters > share L3 cache data while cores within each cluster share the L2 cache. > > The cache affinity of cluster has been proved to improve the Linux kernel > scheduling performance and a patchset has been posted, in which a general > sched_domain for clusters was added and a cluster level was added in the > arch-neutral cpu topology struct like below. > struct cpu_topology { > int thread_id; > int core_id; > int cluster_id; > int package_id; > int llc_id; > cpumask_t thread_sibling; > cpumask_t core_sibling; > cpumask_t cluster_sibling; > cpumask_t llc_sibling; > } > > Also the Kernel Doc: Documentation/devicetree/bindings/cpu/cpu-topology.txt > defines a four-level CPU topology hierarchy like socket/cluster/core/thread. > According to the context, a socket node's child nodes must be one or more > cluster nodes and a cluster node's child nodes must be one or more cluster > nodes/one or more core nodes. > > So let's add the -smp, clusters=* command line support for ARM cpu, so that > future guest os could make use of cluster cpu topology for better scheduling > performance. For ARM machines, a four-level cpu hierarchy can be defined and > it will be sockets/clusters/cores/threads. Because we only support clusters > for ARM cpu currently, a new member "unsigned smp_clusters" is added to the > VirtMachineState structure. > > Signed-off-by: Yanan Wang > --- > include/hw/arm/virt.h | 1 + > qemu-options.hx | 26 +++++++++++++++----------- > softmmu/vl.c | 3 +++ > 3 files changed, 19 insertions(+), 11 deletions(-) > > diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h > index 4a4b98e4a7..5d5d156924 100644 > --- a/include/hw/arm/virt.h > +++ b/include/hw/arm/virt.h > @@ -155,6 +155,7 @@ struct VirtMachineState { > char *pciehb_nodename; > const int *irqmap; > int fdt_size; > + unsigned smp_clusters; > uint32_t clock_phandle; > uint32_t gic_phandle; > uint32_t msi_phandle; > diff --git a/qemu-options.hx b/qemu-options.hx > index fd21002bd6..65343ea23c 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -184,25 +184,29 @@ SRST > ERST > > DEF("smp", HAS_ARG, QEMU_OPTION_smp, > - "-smp [cpus=]n[,maxcpus=cpus][,cores=cores][,threads=threads][,dies=dies][,sockets=sockets]\n" > + "-smp [cpus=]n[,maxcpus=cpus][,clusters=clusters][,cores=cores][,threads=threads][,dies=dies][,sockets=sockets]\n" Please put clusters directly in front of dies in the above list, like it is in the list description below > " set the number of CPUs to 'n' [default=1]\n" > " maxcpus= maximum number of total cpus, including\n" > " offline CPUs for hotplug, etc\n" > - " cores= number of CPU cores on one socket (for PC, it's on one die)\n" > + " cores= number of CPU cores on one socket\n" > + " (it's on one die for PC, and on one cluster for ARM)\n" > " threads= number of threads on one CPU core\n" > + " clusters= number of CPU clusters on one socket (for ARM only)\n" > " dies= number of CPU dies on one socket (for PC only)\n" > " sockets= number of discrete sockets in the system\n", > QEMU_ARCH_ALL) > SRST > -``-smp [cpus=]n[,cores=cores][,threads=threads][,dies=dies][,sockets=sockets][,maxcpus=maxcpus]`` > - Simulate an SMP system with n CPUs. On the PC target, up to 255 CPUs > - are supported. On Sparc32 target, Linux limits the number of usable > - CPUs to 4. For the PC target, the number of cores per die, the > - number of threads per cores, the number of dies per packages and the > - total number of sockets can be specified. Missing values will be > - computed. If any on the three values is given, the total number of > - CPUs n can be omitted. maxcpus specifies the maximum number of > - hotpluggable CPUs. > +``-smp [cpus=]n[,maxcpus=cpus][,clusters=clusters][,cores=cores][,threads=threads][,dies=dies][,sockets=sockets]`` Also move clusters in this list over in front of dies to match the suggested change above. > + Simulate an SMP system with n CPUs. On the PC target, up to 255 > + CPUs are supported. On the Sparc32 target, Linux limits the number > + of usable CPUs to 4. For the PC target, the number of threads per > + core, the number of cores per die, the number of dies per package > + and the total number of sockets can be specified. For the ARM target, > + the number of threads per core, the number of cores per cluster, the > + number of clusters per socket and the total number of sockets can be > + specified. And missing values will be computed. If any of the five > + values is given, the total number of CPUs n can be omitted. Maxcpus > + specifies the maximum number of hotpluggable CPUs. > ERST > > DEF("numa", HAS_ARG, QEMU_OPTION_numa, > diff --git a/softmmu/vl.c b/softmmu/vl.c > index aadb526138..46f5b6b575 100644 > --- a/softmmu/vl.c > +++ b/softmmu/vl.c > @@ -720,6 +720,9 @@ static QemuOptsList qemu_smp_opts = { > }, { > .name = "dies", > .type = QEMU_OPT_NUMBER, > + }, { > + .name = "clusters", > + .type = QEMU_OPT_NUMBER, > }, { > .name = "cores", > .type = QEMU_OPT_NUMBER, > -- > 2.19.1 > Thanks, drew