Re: [Qemu-devel] [PATCH v1 2/5] vl.c: add -smp, dies=* command line support

[Xu, Like]

> -----Original Message-----
> From: Eduardo Habkost [mailto:address@hidden
> Sent: Tuesday, January 15, 2019 4:52 AM
> To: Like Xu <address@hidden>
> Cc: address@hidden; Xu, Like <address@hidden>;
> address@hidden; address@hidden; Michael S. Tsirkin
> <address@hidden>; Marcelo Tosatti <address@hidden>; Marcel
> Apfelbaum <address@hidden>; Paolo Bonzini
> <address@hidden>; Peter Crosthwaite
> <address@hidden>; Richard Henderson <address@hidden>
> Subject: Re: [Qemu-devel] [PATCH v1 2/5] vl.c: add -smp,dies=* command
> line support
> 
> On Mon, Jan 14, 2019 at 08:24:56PM +0800, Like Xu wrote:
> > This patch updates the check rules on legeacy -smp parse from user
> > command and it's designed to obey the same restrictions as
> socket/core/thread model.
> >
> > Signed-off-by: Like Xu <address@hidden>
> 
> This would require the documentation for -smp to be updated.
> qemu-options.hx still says that "cores=" is the number of cores per socket.
[Xu, Like] I'll add more docs in next version and thanks.
> 
> Also, I'm not completely sure we should change the meaning of "cores="
> and smp_cores to be per-die instead of per-socket.  Most machines won't
> have any code for tracking dies, so we probably shouldn't make the extra
> complexity affect all machines.[1]
[Xu, Like] I'd prefer to apply die level in a general way without extra affect.
> 
> What would be the disadvantages of a simple -machine "dies-per-socket"
> option, specific for PC?
[Xu, Like] It may not be a good choice to cut up cpu topo parser logic and
die level is so generic that any machine provided by qemu as far as I know
could benefit from potential socket/die/core/thread model.
> 
> Keeping core-id and smp_cores per-socket instead of per-die also seems
> necessary to keep backwards compatibility on the interface for identifying
> CPU hotplug slots.  Igor, what do you think?
[Xu, Like] The compatibility issue on hotplug from MCP challenge is still being 
evaluated and Igor, what do you think :D ? 
> 
> 
> [1] I would even argue that the rest of the -smp options belong
>     to the machine object, and topology rules should be
>     machine-specific, but cleaning this up will require
>     additional work.
[Xu, Like] I agree and Intel may have another
two cpu topo levels named module and tile from SDM spec for packaging
and that should be machine-specific as proposal if any. However
the die level I believe is much more generic just like core or thread.
> 
> > ---
> >  hmp.c             |  3 +++
> >  hw/core/machine.c | 12 ++++++++++++
> >  vl.c              | 33 ++++++++++++++++++++-------------
> >  3 files changed, 35 insertions(+), 13 deletions(-)
> >
> > diff --git a/hmp.c b/hmp.c
> > index 80aa5ab..05ac133 100644
> > --- a/hmp.c
> > +++ b/hmp.c
> > @@ -3013,6 +3013,9 @@ void hmp_hotpluggable_cpus(Monitor *mon,
> const QDict *qdict)
> >          if (c->has_socket_id) {
> >              monitor_printf(mon, "    socket-id: \"%" PRIu64 "\"\n", c-
> >socket_id);
> >          }
> > +        if (c->has_die_id) {
> > +            monitor_printf(mon, "    die-id: \"%" PRIu64 "\"\n", 
> > c->die_id);
> > +        }
> >          if (c->has_core_id) {
> >              monitor_printf(mon, "    core-id: \"%" PRIu64 "\"\n", 
> > c->core_id);
> >          }
> > diff --git a/hw/core/machine.c b/hw/core/machine.c index
> > 95dc7c3..05bc545 100644
> > --- a/hw/core/machine.c
> > +++ b/hw/core/machine.c
> > @@ -601,6 +601,11 @@ void
> machine_set_cpu_numa_node(MachineState *machine,
> >              return;
> >          }
> >
> > +        if (props->has_die_id && !slot->props.has_die_id) {
> > +            error_setg(errp, "die-id is not supported");
> > +            return;
> > +        }
> > +
> >          if (props->has_socket_id && !slot->props.has_socket_id) {
> >              error_setg(errp, "socket-id is not supported");
> >              return;
> > @@ -615,6 +620,10 @@ void
> machine_set_cpu_numa_node(MachineState *machine,
> >                  continue;
> >          }
> >
> > +        if (props->has_die_id && props->die_id != slot->props.die_id) {
> > +                continue;
> > +        }
> > +
> >          if (props->has_socket_id && props->socket_id != slot-
> >props.socket_id) {
> >                  continue;
> >          }
> > @@ -849,6 +858,9 @@ static char *cpu_slot_to_string(const CPUArchId
> *cpu)
> >      if (cpu->props.has_socket_id) {
> >          g_string_append_printf(s, "socket-id: %"PRId64, cpu-
> >props.socket_id);
> >      }
> > +    if (cpu->props.has_die_id) {
> > +        g_string_append_printf(s, "die-id: %"PRId64, cpu->props.die_id);
> > +    }
> >      if (cpu->props.has_core_id) {
> >          if (s->len) {
> >              g_string_append_printf(s, ", "); diff --git a/vl.c b/vl.c
> > index 9b8ea3f..72be689 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -169,6 +169,7 @@ int win2k_install_hack = 0;  int singlestep = 0;
> > int smp_cpus;  unsigned int max_cpus;
> > +int smp_dies = 1;
> >  int smp_cores = 1;
> >  int smp_threads = 1;
> >  int acpi_enabled = 1;
> > @@ -1208,6 +1209,9 @@ static QemuOptsList qemu_smp_opts = {
> >              .name = "sockets",
> >              .type = QEMU_OPT_NUMBER,
> >          }, {
> > +             .name = "dies",
> > +            .type = QEMU_OPT_NUMBER,
> > +        }, {
> >              .name = "cores",
> >              .type = QEMU_OPT_NUMBER,
> >          }, {
> > @@ -1226,32 +1230,34 @@ static void smp_parse(QemuOpts *opts)
> >      if (opts) {
> >          unsigned cpus    = qemu_opt_get_number(opts, "cpus", 0);
> >          unsigned sockets = qemu_opt_get_number(opts, "sockets", 0);
> > +        unsigned dies = qemu_opt_get_number(opts, "dies", 0);
> >          unsigned cores   = qemu_opt_get_number(opts, "cores", 0);
> >          unsigned threads = qemu_opt_get_number(opts, "threads", 0);
> >
> >          /* compute missing values, prefer sockets over cores over
> > threads */
> > +        dies = dies > 0 ? dies : 1;
> >          if (cpus == 0 || sockets == 0) {
> >              cores = cores > 0 ? cores : 1;
> >              threads = threads > 0 ? threads : 1;
> >              if (cpus == 0) {
> >                  sockets = sockets > 0 ? sockets : 1;
> > -                cpus = cores * threads * sockets;
> > +                cpus = cores * threads * dies * sockets;
> >              } else {
> >                  max_cpus = qemu_opt_get_number(opts, "maxcpus", cpus);
> > -                sockets = max_cpus / (cores * threads);
> > +                sockets = max_cpus / (cores * threads * dies);
> >              }
> >          } else if (cores == 0) {
> >              threads = threads > 0 ? threads : 1;
> > -            cores = cpus / (sockets * threads);
> > +            cores = cpus / (sockets * dies * threads);
> >              cores = cores > 0 ? cores : 1;
> >          } else if (threads == 0) {
> > -            threads = cpus / (cores * sockets);
> > +            threads = cpus / (cores * dies * sockets);
> >              threads = threads > 0 ? threads : 1;
> > -        } else if (sockets * cores * threads < cpus) {
> > +        } else if (sockets * dies * cores * threads < cpus) {
> >              error_report("cpu topology: "
> > -                         "sockets (%u) * cores (%u) * threads (%u) < "
> > +                         "sockets (%u) * dies (%u) * cores (%u) * threads 
> > (%u) < "
> >                           "smp_cpus (%u)",
> > -                         sockets, cores, threads, cpus);
> > +                         sockets, dies, cores, threads, cpus);
> >              exit(1);
> >          }
> >
> > @@ -1262,22 +1268,23 @@ static void smp_parse(QemuOpts *opts)
> >              exit(1);
> >          }
> >
> > -        if (sockets * cores * threads > max_cpus) {
> > +        if (sockets * dies * cores * threads > max_cpus) {
> >              error_report("cpu topology: "
> > -                         "sockets (%u) * cores (%u) * threads (%u) > "
> > +                         "sockets (%u) * dies (%u) * cores (%u) * threads 
> > (%u) > "
> >                           "maxcpus (%u)",
> > -                         sockets, cores, threads, max_cpus);
> > +                         sockets, dies, cores, threads, max_cpus);
> >              exit(1);
> >          }
> >
> > -        if (sockets * cores * threads != max_cpus) {
> > +        if (sockets * dies * cores * threads != max_cpus) {
> >              warn_report("Invalid CPU topology deprecated: "
> > -                        "sockets (%u) * cores (%u) * threads (%u) "
> > +                        "sockets (%u) * dies (%u) * cores (%u) * threads 
> > (%u) "
> >                          "!= maxcpus (%u)",
> > -                        sockets, cores, threads, max_cpus);
> > +                        sockets, dies, cores, threads, max_cpus);
> >          }
> >
> >          smp_cpus = cpus;
> > +        smp_dies = dies;
> >          smp_cores = cores;
> >          smp_threads = threads;
> >      }
> > --
> > 1.8.3.1
> >
> 
> --
> Eduardo