Re: [PATCH v4 1/3] numa: Validate cluster and NUMA node boundary if required

[Alistair Francis <alistair23@gmail.com>]

On Fri, Mar 17, 2023 at 4:29 PM Gavin Shan <gshan@redhat.com> wrote:
>
> For some architectures like ARM64, multiple CPUs in one cluster can be
> associated with different NUMA nodes, which is irregular configuration
> because we shouldn't have this in baremetal environment. The irregular
> configuration causes Linux guest to misbehave, as the following warning
> messages indicate.
>
>   -smp 6,maxcpus=6,sockets=2,clusters=1,cores=3,threads=1 \
>   -numa node,nodeid=0,cpus=0-1,memdev=ram0                \
>   -numa node,nodeid=1,cpus=2-3,memdev=ram1                \
>   -numa node,nodeid=2,cpus=4-5,memdev=ram2                \
>
>   ------------[ cut here ]------------
>   WARNING: CPU: 0 PID: 1 at kernel/sched/topology.c:2271 build_sched_domains+0x284/0x910
>   Modules linked in:
>   CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.14.0-268.el9.aarch64 #1
>   pstate: 00400005 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>   pc : build_sched_domains+0x284/0x910
>   lr : build_sched_domains+0x184/0x910
>   sp : ffff80000804bd50
>   x29: ffff80000804bd50 x28: 0000000000000002 x27: 0000000000000000
>   x26: ffff800009cf9a80 x25: 0000000000000000 x24: ffff800009cbf840
>   x23: ffff000080325000 x22: ffff0000005df800 x21: ffff80000a4ce508
>   x20: 0000000000000000 x19: ffff000080324440 x18: 0000000000000014
>   x17: 00000000388925c0 x16: 000000005386a066 x15: 000000009c10cc2e
>   x14: 00000000000001c0 x13: 0000000000000001 x12: ffff00007fffb1a0
>   x11: ffff00007fffb180 x10: ffff80000a4ce508 x9 : 0000000000000041
>   x8 : ffff80000a4ce500 x7 : ffff80000a4cf920 x6 : 0000000000000001
>   x5 : 0000000000000001 x4 : 0000000000000007 x3 : 0000000000000002
>   x2 : 0000000000001000 x1 : ffff80000a4cf928 x0 : 0000000000000001
>   Call trace:
>    build_sched_domains+0x284/0x910
>    sched_init_domains+0xac/0xe0
>    sched_init_smp+0x48/0xc8
>    kernel_init_freeable+0x140/0x1ac
>    kernel_init+0x28/0x140
>    ret_from_fork+0x10/0x20
>
> Improve the situation to warn when multiple CPUs in one cluster have
> been associated with different NUMA nodes. However, one NUMA node is
> allowed to be associated with different clusters.
>
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> Acked-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Acked-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  hw/core/machine.c   | 42 ++++++++++++++++++++++++++++++++++++++++++
>  include/hw/boards.h |  1 +
>  2 files changed, 43 insertions(+)
>
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 45e3d24fdc..a2329f975d 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -1255,6 +1255,45 @@ static void machine_numa_finish_cpu_init(MachineState *machine)
>      g_string_free(s, true);
>  }
>
> +static void validate_cpu_cluster_to_numa_boundary(MachineState *ms)
> +{
> +    MachineClass *mc = MACHINE_GET_CLASS(ms);
> +    NumaState *state = ms->numa_state;
> +    const CPUArchIdList *possible_cpus = mc->possible_cpu_arch_ids(ms);
> +    const CPUArchId *cpus = possible_cpus->cpus;
> +    int i, j;
> +
> +    if (state->num_nodes <= 1 || possible_cpus->len <= 1) {
> +        return;
> +    }
> +
> +    /*
> +     * The Linux scheduling domain can't be parsed when the multiple CPUs
> +     * in one cluster have been associated with different NUMA nodes. However,
> +     * it's fine to associate one NUMA node with CPUs in different clusters.
> +     */
> +    for (i = 0; i < possible_cpus->len; i++) {
> +        for (j = i + 1; j < possible_cpus->len; j++) {
> +            if (cpus[i].props.has_socket_id &&
> +                cpus[i].props.has_cluster_id &&
> +                cpus[i].props.has_node_id &&
> +                cpus[j].props.has_socket_id &&
> +                cpus[j].props.has_cluster_id &&
> +                cpus[j].props.has_node_id &&
> +                cpus[i].props.socket_id == cpus[j].props.socket_id &&
> +                cpus[i].props.cluster_id == cpus[j].props.cluster_id &&
> +                cpus[i].props.node_id != cpus[j].props.node_id) {
> +                warn_report("CPU-%d and CPU-%d in socket-%ld-cluster-%ld "
> +                             "have been associated with node-%ld and node-%ld "
> +                             "respectively. It can cause OSes like Linux to "
> +                             "misbehave", i, j, cpus[i].props.socket_id,
> +                             cpus[i].props.cluster_id, cpus[i].props.node_id,
> +                             cpus[j].props.node_id);
> +            }
> +        }
> +    }
> +}
> +
>  MemoryRegion *machine_consume_memdev(MachineState *machine,
>                                       HostMemoryBackend *backend)
>  {
> @@ -1340,6 +1379,9 @@ void machine_run_board_init(MachineState *machine, const char *mem_path, Error *
>          numa_complete_configuration(machine);
>          if (machine->numa_state->num_nodes) {
>              machine_numa_finish_cpu_init(machine);
> +            if (machine_class->cpu_cluster_has_numa_boundary) {
> +                validate_cpu_cluster_to_numa_boundary(machine);
> +            }
>          }
>      }
>
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index 6fbbfd56c8..c9793b2789 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -273,6 +273,7 @@ struct MachineClass {
>      bool nvdimm_supported;
>      bool numa_mem_supported;
>      bool auto_enable_numa;
> +    bool cpu_cluster_has_numa_boundary;
>      SMPCompatProps smp_props;
>      const char *default_ram_id;
>
> --
> 2.23.0
>
>