On Mon, May 27, 2019 at 03:52:30PM +0200, Laurent Vivier wrote:
> On 27/05/2019 14:50, Igor Mammedov wrote:
> > On Mon, 27 May 2019 08:55:49 +0200
> > Laurent Vivier <lviv...@redhat.com> wrote:
> >
> >> On 24/05/2019 22:14, Eduardo Habkost wrote:
> >>> On Fri, May 24, 2019 at 04:39:12PM +0200, Laurent Vivier wrote:
> >>>> On 24/05/2019 16:10, Igor Mammedov wrote:
> >>>>> On Fri, 24 May 2019 12:35:21 +0200
> >>>>> Laurent Vivier <lviv...@redhat.com> wrote:
> >>>>>
> >>>>>> On pseries, core-ids are strongly binded to a node-id by the command
> >>>>>> line option. If an user tries to add a CPU to the wrong node, he has
> >>>>>> an error but it is not really helpful:
> >>>>>>
> >>>>>> qemu-system-ppc64 ... -smp
> >>>>>> 1,maxcpus=64,cores=1,threads=1,sockets=1 \
> >>>>>> -numa node,nodeid=0 -numa node,nodeid=1 ...
> >>>>>>
> >>>>>> (qemu) device_add power9_v2.0-spapr-cpu-core,core-id=30,node-id=1
> >>>>>> Error: node-id=1 must match numa node specified with -numa option
> >>>>>>
> >>>>>> This patch improves this error message by giving to the user the good
> >>>>>> topology information (node-id, socket-id and thread-id if they are
> >>>>>> available) to use with the core-id he's providing:
> >>>>>>
> >>>>>> Error: node-id=1 must match numa node specified with -numa option
> >>>>>> 'node-id 0'
> >>>>>>
> >>>>>> Signed-off-by: Laurent Vivier <lviv...@redhat.com>
> >>>>>> ---
> >>>>>>
> >>>>>> Notes:
> >>>>>> v3: only add the topology to the existing message
> >>>>>> As suggested by Igor replace
> >>>>>> Error: core-id 30 can only be plugged into node-id 0
> >>>>>> by
> >>>>>> Error: node-id=1 must match numa node specified with
> >>>>>> -numa option 'node-id 0'
> >>>>>> v2: display full topology in the error message
> >>>>>>>>> numa.c | 25 ++++++++++++++++++++++++-
> >>>>>> 1 file changed, 24 insertions(+), 1 deletion(-)
> >>>>>>
> >>>>>> diff --git a/numa.c b/numa.c
> >>>>>> index 3875e1efda3a..7882ec294be4 100644
> >>>>>> --- a/numa.c
> >>>>>> +++ b/numa.c
> >>>>>> @@ -458,6 +458,27 @@ void qmp_set_numa_node(NumaOptions *cmd, Error
> >>>>>> **errp)
> >>>>>> set_numa_options(MACHINE(qdev_get_machine()), cmd, errp);
> >>>>>> }
> >>>>>> +static char *cpu_topology_to_string(const CPUArchId *cpu)
> >>>>>> +{
> >>>>>> + GString *s = g_string_new(NULL);
> >>>>>> + if (cpu->props.has_socket_id) {
> >>>>>> + g_string_append_printf(s, "socket-id %"PRId64,
> >>>>>> cpu->props.socket_id);
> >>>>>> + }
> >>>>>> + if (cpu->props.has_node_id) {
> >>>>>> + if (s->len) {
> >>>>>> + g_string_append_printf(s, ", ");
> >>>>>> + }
> >>>>>> + g_string_append_printf(s, "node-id %"PRId64,
> >>>>>> cpu->props.node_id);
> >>>>>> + }
> >>>>>> + if (cpu->props.has_thread_id) {
> >>>>>> + if (s->len) {
> >>>>>> + g_string_append_printf(s, ", ");
> >>>>>> + }
> >>>>>> + g_string_append_printf(s, "thread-id %"PRId64,
> >>>>>> cpu->props.thread_id);
> >>>>>> + }
> >>>>>> + return g_string_free(s, false);
> >>>>>> +}
> >>>>>
> >>>>> turns out we already have such helper: cpu_slot_to_string()
> >>>>
> >>>> It doesn't display the node-id but the core-id. And node-id is what we
> >>>> need
> >>>> to know.
> >>>
> >>> I'm confused about what you are trying to do here.
> >>>
> >>> On v1, the message looked like:
> >>> Error: core-id 30 can only be plugged into node-id 0
> >>>
> >>> which is probably good for spapr.
> >>>
> >>>
> >>> Then I suggested you added the other cpu->props fields. e.g. on
> >>> PC the message would look like:
> >>> Error: socket-id 20, core-id 30, thread-id 40 can only be plugged
> >>> into node-id 0
> >>>
> >>>
> >>> But you sent a v2 patch that would print this on PC:
> >>> Error: core-id 30 can only be plugged into socket-id 20, node-id 0,
> >>> thread-id 40
> >>>
> >>> which doesn't make sense to me.
> >>>
> >>>
> >>> Then in a reply to v2, Igor suggested:
> >>>
> >>> error_setg(errp, "node-id=%d must match numa node specified "
> >>> "with -numa option '%s'", node_id, topology);
> >>>
> >>>
> >>> Igor suggest would address the problem above. I expected it to become:
> >>> node-id=0 must match numa node specified with -numa option core-id=30
> >>> and on PC:
> >>> node-id=0 must match numa node specified with -numa option
> >>> socket-id=20,core-id=30,thread-id=40
> >>>
> >>> Or maybe it could include the input node-id too:
> >>> node-id=0 must match numa node specified with -numa option
> >>> node-id=1,core-id=30
> >>> and on PC:
> >>> node-id=0 must match numa node specified with -numa option
> >>> node-id=1,socket-id=20,core-id=30,thread-id=40
> >>>
> >>> Both options would work.
> >>>
> >>>
> >>> But you implemented code that would print:
> >>> Error: node-id=0 must match numa node specified with -numa option
> >>> 'node-id 1'
> >>> and on PC it would print:
> >>> Error: node-id=0 must match numa node specified with -numa option
> >>> 'socket-id 20 node-id 1 thread-id=40'
> >>>
> >>> which doesn't make sense to me.
> >>>
> >>>
> >>> I was expecting something like:
> >>> Error: CPU slot core-id=30 is bound to node-id 0, but node-id 1 was
> >>> specified
> >>> and on PC:
> >>> Error: CPU slot socket-id=20,core-id=30,thread-id=40 is bound to
> >>> node-id 0, but node-id 1 was specified
> >>>
> >>>
> >>
> >> The idea is to provide the information to the user to help him to know
> >> where the cpu can be plugged when it cannot on the node-id he originally
> >> provided.
> >>
> >> So all the solutions you propose sounds good to me.
> >>
> >> I only need you and Igor agree on the same one.
> >
> > We with Eduardo basically agree on contents/set of properties to print,
> > it is only different phrasing (Eduardo's suggestion is better than what we
> > have now).
> > But lets get to what problem you are going to fix/improve. SO I've went
> > ahead and tried
> > with following CLI:
> >
> > qemu-system-x86_64 -smp 1,maxcpus=4 -numa node,cpus=0-1 -numa
> > node,cpus=2-3 -monitor stdio -device
> > qemu64-x86_64-cpu,socket-id=1,core-id=0,thread-id=0,node-id=1
> >
> > end it errored out with:
> >
> > qemu-system-x86_64: -device
> > qemu64-x86_64-cpu,socket-id=1,core-id=0,thread-id=0,node-id=1: node-id=1
> > must match numa node specified with -numa option
> >
> > As you see we already have all user provide properties for cpu (including
> > invalid ones) reported,
> > what we are missing is suggestion for valid node-id. How about following
> > error message:
> >
> > qemu-system-x86_64: -device
> > qemu64-x86_64-cpu,socket-id=1,core-id=0,thread-id=0,node-id=1: invalid
> > node-id, must be 0
>
> The case I'm worrying about is when the cpu is hotplugged: we don't have the
> "-device ..." information.
>
> $ qemu-system-ppc64 -nodefaults -nographic -monitor stdio -m 1G -smp
> 1,maxcpus=64,cores=1,threads=1,sockets=1 -numa node,nodeid=0 -numa
> node,nodeid=1
> QEMU 3.0.1 monitor - type 'help' for more information
> (qemu) device_add power8_v2.0-spapr-cpu-core,core-id=30,node-id=1
> node-id=1 must match numa node specified with -numa option
>
> So you can see the needed information is missing.
What kind of essential information would be missing if we
followed Igor's suggestion?
(qemu) device_add power8_v2.0-spapr-cpu-core,core-id=30,node-id=1
invalid node-id, must be 0
If you really want to identify core-id on the error message (like
you did in v1 and v2), it seems OK too. It just requires extra
work because on PC core-id alone doesn't identify a CPU slot (you
need socket-id, core-id, thread-id).
--
Eduardo
