70 lines
2.7 KiB
Diff
70 lines
2.7 KiB
Diff
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From 1fab7ee365c8daccedd19d3a1be56babe36afcc6 Mon Sep 17 00:00:00 2001
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From: Yanan Wang <wangyanan55@huawei.com>
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Date: Fri, 7 Jan 2022 16:32:27 +0800
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Subject: [PATCH 15/24] hw/arm/virt: Support CPU cluster on ARM virt machine
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ARM64 machines like Kunpeng Family Server Chips have a level
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of hardware topology in which a group of CPU cores share L3
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cache tag or L2 cache. For example, Kunpeng 920 typically
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has 6 or 8 clusters in each NUMA node (also represent range
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of CPU die), and each cluster has 4 CPU cores. All clusters
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share L3 cache data, but CPU cores in each cluster share a
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local L3 tag.
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Running a guest kernel with Cluster-Aware Scheduling on the
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Hosts which have physical clusters, if we can design a vCPU
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topology with cluster level for guest kernel and then have
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a dedicated vCPU pinning, the guest will gain scheduling
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performance improvement from cache affinity of CPU cluster.
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So let's enable the support for this new parameter on ARM
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virt machines. After this patch, we can define a 4-level
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CPU hierarchy like: cpus=*,maxcpus=*,sockets=*,clusters=*,
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cores=*,threads=*.
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Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
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Reviewed-by: Andrew Jones <drjones@redhat.com>
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Message-id: 20220107083232.16256-2-wangyanan55@huawei.com
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Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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---
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hw/arm/virt.c | 1 +
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qemu-options.hx | 10 ++++++++++
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2 files changed, 11 insertions(+)
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diff --git a/hw/arm/virt.c b/hw/arm/virt.c
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index 3c972fdab0..6ca9cbe2cf 100644
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--- a/hw/arm/virt.c
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+++ b/hw/arm/virt.c
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@@ -2704,6 +2704,7 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
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hc->unplug_request = virt_machine_device_unplug_request_cb;
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hc->unplug = virt_machine_device_unplug_cb;
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mc->nvdimm_supported = true;
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+ mc->smp_props.clusters_supported = true;
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mc->auto_enable_numa_with_memhp = true;
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mc->auto_enable_numa_with_memdev = true;
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mc->default_ram_id = "mach-virt.ram";
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diff --git a/qemu-options.hx b/qemu-options.hx
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index 0f26f7dad7..74d335e4c3 100644
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--- a/qemu-options.hx
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+++ b/qemu-options.hx
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@@ -277,6 +277,16 @@ SRST
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-smp 16,sockets=2,dies=2,cores=2,threads=2,maxcpus=16
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+ The following sub-option defines a CPU topology hierarchy (2 sockets
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+ totally on the machine, 2 clusters per socket, 2 cores per cluster,
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+ 2 threads per core) for ARM virt machines which support sockets/clusters
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+ /cores/threads. Some members of the option can be omitted but their values
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+ will be automatically computed:
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+
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+ ::
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+
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+ -smp 16,sockets=2,clusters=2,cores=2,threads=2,maxcpus=16
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+
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Historically preference was given to the coarsest topology parameters
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when computing missing values (ie sockets preferred over cores, which
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were preferred over threads), however, this behaviour is considered
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--
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2.27.0
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