On Tue, Apr 13, 2021 at 04:31:45PM +0800, Yanan Wang wrote:
> There is a separate function virt_smp_parse() in hw/virt/arm.c used
> to parse cpu topology for the ARM machines. So add parsing of -smp
> cluster parameter in it, then total number of logical cpus will be
> calculated like: max_cpus = sockets * clusters * cores * threads.
>
> In virt_smp_parse(), the computing logic of missing values prefers
> cores over sockets over threads. And for compatibility, the value
> of clusters will be set as default 1 if not explicitly specified.
>
> Signed-off-by: Yanan Wang <wangyana...@huawei.com>
> ---
> hw/arm/virt.c | 32 ++++++++++++++++++--------------
> 1 file changed, 18 insertions(+), 14 deletions(-)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 57ef961cb5..51797628db 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -2639,35 +2639,38 @@ static void virt_smp_parse(MachineState *ms, QemuOpts
> *opts)
> if (opts) {
> unsigned cpus = qemu_opt_get_number(opts, "cpus", 0);
> unsigned sockets = qemu_opt_get_number(opts, "sockets", 0);
> + unsigned clusters = qemu_opt_get_number(opts, "clusters", 1);
> unsigned cores = qemu_opt_get_number(opts, "cores", 0);
> unsigned threads = qemu_opt_get_number(opts, "threads", 0);
> + VirtMachineState *vms = VIRT_MACHINE(ms);
>
> /*
> - * Compute missing values; prefer cores over sockets and
> - * sockets over threads.
> + * Compute missing values; prefer cores over sockets and sockets
> + * over threads. For compatibility, value of clusters will have
> + * been set as default 1 if not explicitly specified.
> */
> if (cpus == 0 || cores == 0) {
> sockets = sockets > 0 ? sockets : 1;
> threads = threads > 0 ? threads : 1;
> if (cpus == 0) {
> cores = cores > 0 ? cores : 1;
> - cpus = cores * threads * sockets;
> + cpus = sockets * clusters * cores * threads;
> } else {
> ms->smp.max_cpus = qemu_opt_get_number(opts, "maxcpus",
> cpus);
> - cores = ms->smp.max_cpus / (sockets * threads);
> + cores = ms->smp.max_cpus / (sockets * clusters * threads);
> }
> } else if (sockets == 0) {
> threads = threads > 0 ? threads : 1;
> - sockets = cpus / (cores * threads);
> + sockets = cpus / (clusters * cores * threads);
> sockets = sockets > 0 ? sockets : 1;
If we initialize clusters to zero instead of one and add lines in
'cpus == 0 || cores == 0' and 'sockets == 0' like
'clusters = clusters > 0 ? clusters : 1' as needed, then I think we can
add
} else if (clusters == 0) {
threads = threads > 0 ? threads : 1;
clusters = cpus / (sockets * cores * thread);
clusters = clusters > 0 ? clusters : 1;
}
here.
> } else if (threads == 0) {
> - threads = cpus / (cores * sockets);
> + threads = cpus / (sockets * clusters * cores);
> threads = threads > 0 ? threads : 1;
> - } else if (sockets * cores * threads < cpus) {
> + } else if (sockets * clusters * cores * threads < cpus) {
> error_report("cpu topology: "
> - "sockets (%u) * cores (%u) * threads (%u) < "
> - "smp_cpus (%u)",
> - sockets, cores, threads, cpus);
> + "sockets (%u) * clusters (%u) * cores (%u) * "
> + "threads (%u) < smp_cpus (%u)",
> + sockets, clusters, cores, threads, cpus);
> exit(1);
> }
>
> @@ -2678,11 +2681,11 @@ static void virt_smp_parse(MachineState *ms, QemuOpts
> *opts)
> exit(1);
> }
>
> - if (sockets * cores * threads != ms->smp.max_cpus) {
> + if (sockets * clusters * cores * threads != ms->smp.max_cpus) {
> error_report("cpu topology: "
> - "sockets (%u) * cores (%u) * threads (%u)"
> - "!= maxcpus (%u)",
> - sockets, cores, threads,
> + "sockets (%u) * clusters (%u) * cores (%u) * "
> + "threads (%u) != maxcpus (%u)",
> + sockets, clusters, cores, threads,
> ms->smp.max_cpus);
> exit(1);
> }
> @@ -2691,6 +2694,7 @@ static void virt_smp_parse(MachineState *ms, QemuOpts
> *opts)
> ms->smp.cores = cores;
> ms->smp.threads = threads;
> ms->smp.sockets = sockets;
> + vms->smp_clusters = clusters;
> }
>
> if (ms->smp.cpus > 1) {
> --
> 2.19.1
>
Thanks,
drew
