From: Igor Mammedov <imammedo@redhat.com>
To: Babu Moger <babu.moger@amd.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"ehabkost@redhat.com" <ehabkost@redhat.com>,
"rth@twiddle.net" <rth@twiddle.net>
Subject: Re: [PATCH v2 1/3] hw/i386: Initialize topo_ids from CpuInstanceProperties
Date: Mon, 13 Jul 2020 19:32:21 +0200 [thread overview]
Message-ID: <20200713193221.27674630@redhat.com> (raw)
In-Reply-To: <47dc6238-bb71-d679-f58a-f574eb36d572@amd.com>
On Mon, 13 Jul 2020 11:43:33 -0500
Babu Moger <babu.moger@amd.com> wrote:
> On 7/13/20 11:17 AM, Igor Mammedov wrote:
> > On Mon, 13 Jul 2020 10:02:22 -0500
> > Babu Moger <babu.moger@amd.com> wrote:
> >
> >>> -----Original Message-----
> >>> From: Igor Mammedov <imammedo@redhat.com>
> >>> Sent: Monday, July 13, 2020 4:08 AM
> >>> To: Moger, Babu <Babu.Moger@amd.com>
> >>> Cc: pbonzini@redhat.com; rth@twiddle.net; ehabkost@redhat.com; qemu-
> >>> devel@nongnu.org
> >>> Subject: Re: [PATCH v2 1/3] hw/i386: Initialize topo_ids from
> >>> CpuInstanceProperties
> > [...]
> >>>> +
> >>>> +/*
> >>>> + * Initialize topo_ids from CpuInstanceProperties
> >>>> + * node_id in CpuInstanceProperties(or in CPU device) is a sequential
> >>>> + * number, but while building the topology
> >>>
> >>>> we need to separate it for
> >>>> + * each socket(mod nodes_per_pkg).
> >>> could you clarify a bit more on why this is necessary?
> >>
> >> If you have two sockets and 4 numa nodes, node_id in CpuInstanceProperties
> >> will be number sequentially as 0, 1, 2, 3. But in EPYC topology, it will
> >> be 0, 1, 0, 1( Basically mod % number of nodes per socket).
> >
> > I'm confused, let's suppose we have 2 EPYC sockets with 2 nodes per socket
> > so APIC id woulbe be composed like:
> >
> > 1st socket
> > pkg_id(0) | node_id(0)
> > pkg_id(0) | node_id(1)
> >
> > 2nd socket
> > pkg_id(1) | node_id(0)
> > pkg_id(1) | node_id(1)
> >
> > if that's the case, then EPYC's node_id here doesn't look like
> > a NUMA node in the sense it's usually used
> > (above config would have 4 different memory controllers => 4 conventional NUMA nodes).
>
> EPIC model uses combination of socket id and node id to identify the numa
> nodes. So, it internally uses all the information.
well with above values, EPYC's node_id doesn't look like it's specifying
a machine numa node, but rather a node index within single socket. In which
case, it doesn't make much sense calling it NUMA node_id, it's rather some
index within a socket. (it starts looking like terminology is all mixed up)
If you have access to a milti-socket EPYC machine, can you dump and post here
its apic ids, pls?
>
> >
> > I wonder if linux guest actually uses node_id encoded in apic id for
> > configuring/checking numa structures, or it just uses whatever ACPI SRAT
> > table provided.
> >
> >>>> + */
> >>>> +static inline void x86_init_topo_ids(X86CPUTopoInfo *topo_info,
> >>>> + CpuInstanceProperties props,
> >>>> + X86CPUTopoIDs *topo_ids) {
> >>>> + topo_ids->smt_id = props.has_thread_id ? props.thread_id : 0;
> >>>> + topo_ids->core_id = props.has_core_id ? props.core_id : 0;
> >>>> + topo_ids->die_id = props.has_die_id ? props.die_id : 0;
> >>>> + topo_ids->node_id = props.has_node_id ?
> >>>> + props.node_id % MAX(topo_info->nodes_per_pkg, 1) : 0;
> >>>> + topo_ids->pkg_id = props.has_socket_id ? props.socket_id : 0; }
> >>>> /*
> >>>> * Make APIC ID for the CPU 'cpu_index'
> >>>> *
> >>>>
> >>
> >
>
next prev parent reply other threads:[~2020-07-13 17:33 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-01 17:30 [PATCH v2 0/3] Fix couple of issues with AMD topology Babu Moger
2020-07-01 17:31 ` [PATCH v2 1/3] hw/i386: Initialize topo_ids from CpuInstanceProperties Babu Moger
2020-07-13 9:08 ` Igor Mammedov
2020-07-13 15:02 ` Babu Moger
2020-07-13 16:17 ` Igor Mammedov
2020-07-13 16:43 ` Babu Moger
2020-07-13 17:32 ` Igor Mammedov [this message]
2020-07-13 19:30 ` Babu Moger
2020-07-14 16:41 ` Igor Mammedov
2020-07-14 17:26 ` Babu Moger
2020-07-14 18:26 ` Igor Mammedov
2020-07-24 17:05 ` Igor Mammedov
2020-07-27 15:49 ` Babu Moger
2020-07-27 17:14 ` Igor Mammedov
2020-07-27 23:59 ` Babu Moger
2020-07-29 14:12 ` Igor Mammedov
2020-07-29 21:22 ` Babu Moger
2020-07-30 11:27 ` Igor Mammedov
2020-07-01 17:31 ` [PATCH v2 2/3] hw/i386: Build apic_id " Babu Moger
2020-07-13 9:15 ` Igor Mammedov
2020-07-13 15:00 ` Babu Moger
2020-07-01 17:31 ` [PATCH v2 3/3] hw/386: Fix uninitialized memory with -device and CPU hotplug Babu Moger
2020-07-27 16:36 ` Igor Mammedov
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