> From: wangyanan (Y) > > Hi Salil, > > On 2021/5/17 23:17, Salil Mehta wrote: > >> From: Qemu-devel > >> [mailto:qemu-devel-bounces+salil.mehta=huawei....@nongnu.org] On Behalf Of > >> Yanan Wang > >> Sent: Sunday, May 16, 2021 11:32 AM > >> To: Peter Maydell <peter.mayd...@linaro.org>; Paolo Bonzini > >> <pbonz...@redhat.com>; Andrew Jones <drjo...@redhat.com>; Michael S . > >> Tsirkin > >> <m...@redhat.com>; Igor Mammedov <imamm...@redhat.com>; Shannon Zhao > >> <shannon.zha...@gmail.com>; qemu-devel@nongnu.org; qemu-...@nongnu.org > >> Cc: Song Bao Hua (Barry Song) <song.bao....@hisilicon.com>; Philippe > >> Mathieu-Daudé <phi...@redhat.com>; wangyanan (Y) <wangyana...@huawei.com>; > >> Zengtao (B) <prime.z...@hisilicon.com>; Wanghaibin (D) > >> <wanghaibin.w...@huawei.com>; yuzenghui <yuzeng...@huawei.com>; yangyicong > >> <yangyic...@huawei.com>; zhukeqian <zhukeqi...@huawei.com> > >> Subject: [RFC PATCH v3 4/4] hw/arm/virt: Parse -smp cluster parameter in > >> virt_smp_parse > >> > >> 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. > >> > >> Note, we will assume multi-cluster in one socket is not supported > >> and default the value of clusters to 1, if it's not explicitly > >> specified in -smp cmdline. > >> > >> 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 7de822e491..678d5ef36c 100644 > >> --- a/hw/arm/virt.c > >> +++ b/hw/arm/virt.c > >> @@ -2642,8 +2642,8 @@ static int virt_kvm_type(MachineState *ms, const char > >> *type_str) > >> * with the -smp cmdlines when parsing them. > >> * > >> * We require that at least one of cpus or maxcpus must be provided. > >> - * Threads will default to 1 if not provided. Sockets and cores must > >> - * be either both provided or both not. > >> + * Clusters and threads will default to 1 if they are not provided. > >> + * Sockets and cores must be either both provided or both not. > >> * > >> * Note, if neither sockets nor cores are specified, we will calculate > >> * all the missing values just like smp_parse() does, but will disable > >> @@ -2652,15 +2652,18 @@ static int virt_kvm_type(MachineState *ms, const > >> char > >> *type_str) > >> static void virt_smp_parse(MachineState *ms, QemuOpts *opts) > >> { > >> VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(ms); > >> + VirtMachineState *vms = VIRT_MACHINE(ms); > >> > >> if (opts) { > >> unsigned cpus = qemu_opt_get_number(opts, "cpus", 0); > >> unsigned maxcpus = qemu_opt_get_number(opts, "maxcpus", 0); > >> unsigned sockets = qemu_opt_get_number(opts, "sockets", 0); > >> + unsigned clusters = qemu_opt_get_number(opts, "clusters", 0); > >> unsigned cores = qemu_opt_get_number(opts, "cores", 0); > >> unsigned threads = qemu_opt_get_number(opts, "threads", 0); > >> > >> - /* Default threads to 1 if not provided */ > >> + /* Default clusters and threads to 1 if not provided */ > >> + clusters = clusters > 0 ? clusters : 1; > >> threads = threads > 0 ? threads : 1; > >> > >> if (cpus == 0 && maxcpus == 0) { > >> @@ -2676,13 +2679,13 @@ static void virt_smp_parse(MachineState *ms, > >> QemuOpts > >> *opts) > >> cores = 1; > >> if (cpus == 0) { > >> sockets = 1; > >> - cpus = sockets * cores * threads; > >> + cpus = sockets * clusters * cores * threads; > >> } else { > >> maxcpus = maxcpus > 0 ? maxcpus : cpus; > >> - sockets = maxcpus / (cores * threads); > >> + sockets = maxcpus / (clusters * cores * threads); > >> } > >> } else if (sockets > 0 && cores > 0) { > >> - cpus = cpus > 0 ? cpus : sockets * cores * threads; > >> + cpus = cpus > 0 ? cpus : sockets * clusters * cores * threads; > >> maxcpus = maxcpus > 0 ? maxcpus : cpus; > >> } else { > >> error_report("sockets and cores must be both provided " > >> @@ -2695,25 +2698,26 @@ static void virt_smp_parse(MachineState *ms, > >> QemuOpts > >> *opts) > >> exit(1); > >> } > >> > >> - if (sockets * cores * threads < cpus) { > >> + 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); > >> } > >> > >> - if (sockets * cores * threads != maxcpus) { > >> + if (sockets * clusters * cores * threads != maxcpus) { > >> error_report("cpu topology: " > >> - "sockets (%u) * cores (%u) * threads (%u) " > >> - "!= maxcpus (%u)", > >> - sockets, cores, threads, maxcpus); > >> + "sockets (%u) * clusters (%u) * cores (%u) * " > >> + "threads (%u) != maxcpus (%u)", > >> + sockets, clusters, cores, threads, maxcpus); > >> exit(1); > >> } > >> > >> ms->smp.cpus = cpus; > >> ms->smp.max_cpus = maxcpus; > >> ms->smp.sockets = sockets; > >> + vms->smp_clusters = clusters; > > > > This variable naming *smp_clusters* looks out-of-sorts. I thought a similar > > variable *smp_cpus* was destined to be removed for the reason given in below > > link - a patch by Andrew Jones? > > > > Link: https://lists.gnu.org/archive/html/qemu-arm/2020-12/msg00418.html > > > > Am I missing anything here? > The smp_clusters is added in VirtMachineState and nowhere else because > it's currently only used for ARM. But I think maybe I should also move it to > CpuTopology structure like [1] is doing to move dies to CpuTopology.
yes, that’s the idea. It is always good to have right place holders so that the code comprehension/usage(in this case) becomes easy and obvious. > > Move clusters to CpuTopology won't affect other architectures that don't > support it yet, and will also make it easy if they want to in the future. > > [1] From Paolo: > https://patchwork.kernel.org/project/qemu-devel/patch/20210513162901.131023 > 9-10-pbonz...@redhat.com/ sure. > > Thanks, > Yanan > > Salil. > > > >> ms->smp.cores = cores; > >> ms->smp.threads = threads; > >> }
