From: Andrew Jones <drjones@redhat.com>
To: Yanan Wang <wangyanan55@huawei.com>
Cc: Barry Song <song.bao.hua@hisilicon.com>,
Peter Maydell <peter.maydell@linaro.org>,
"Michael S . Tsirkin" <mst@redhat.com>,
wanghaibin.wang@huawei.com, qemu-devel@nongnu.org,
yangyicong@huawei.com, Shannon Zhao <shannon.zhaosl@gmail.com>,
qemu-arm@nongnu.org, Alistair Francis <alistair.francis@wdc.com>,
prime.zeng@hisilicon.com, Igor Mammedov <imammedo@redhat.com>,
yuzenghui@huawei.com, Paolo Bonzini <pbonzini@redhat.com>,
zhukeqian1@huawei.com, Jiajie Li <lijiajie11@huawei.com>,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [RFC PATCH v2 1/4] vl.c: Add -smp, clusters=* command line support for ARM cpu
Date: Wed, 28 Apr 2021 12:23:53 +0200 [thread overview]
Message-ID: <20210428102353.cfjvzss56c4zwb4y@gator> (raw)
In-Reply-To: <20210413083147.34236-2-wangyanan55@huawei.com>
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 <wangyanan55@huawei.com>
> ---
> 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
next prev parent reply other threads:[~2021-04-28 10:24 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-13 8:31 [RFC PATCH v2 0/4] hw/arm/virt: Introduce cluster cpu topology support Yanan Wang
2021-04-13 8:31 ` [RFC PATCH v2 1/4] vl.c: Add -smp, clusters=* command line support for ARM cpu Yanan Wang
2021-04-28 10:23 ` Andrew Jones [this message]
2021-04-29 1:22 ` wangyanan (Y)
2021-04-13 8:31 ` [RFC PATCH v2 2/4] hw/arm/virt: Parse -smp cluster parameter in virt_smp_parse Yanan Wang
2021-04-28 10:31 ` Andrew Jones
2021-04-29 2:14 ` wangyanan (Y)
2021-04-29 7:16 ` Andrew Jones
2021-04-29 8:56 ` wangyanan (Y)
2021-04-29 11:02 ` Andrew Jones
2021-04-30 5:09 ` wangyanan (Y)
2021-04-30 6:41 ` Andrew Jones
2021-04-30 7:01 ` Andrew Jones
2021-04-30 9:33 ` wangyanan (Y)
2021-04-30 10:49 ` Andrew Jones
2021-05-06 7:04 ` wangyanan (Y)
2021-04-30 8:59 ` wangyanan (Y)
2021-04-30 10:48 ` Andrew Jones
2021-04-13 8:31 ` [RFC PATCH v2 3/4] hw/arm/virt-acpi-build: Add cluster level for PPTT table Yanan Wang
2021-04-28 10:41 ` Andrew Jones
2021-04-13 8:31 ` [RFC PATCH v2 4/4] hw/arm/virt: Add cluster level for device tree Yanan Wang
2021-04-28 10:46 ` Andrew Jones
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