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numa: Print warning if no node is assigned to a CPU

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We need all possible CPUs (including hotplug ones) to be present in the
SRAT when QEMU starts. QEMU already does that correctly today, the only
problem is that when a CPU is omitted from the NUMA configuration, it is
silently assigned to node 0.

Check if all CPUs up to max_cpus are present in the NUMA configuration
and warn about missing CPUs.

Make it just a warning, to allow management software to be updated if
necessary. In the future we may make it a fatal error instead.

Command-line examples:

* Correct, no warning:

  $ qemu-system-x86_64 -smp 2,maxcpus=4
  $ qemu-system-x86_64 -smp 2,maxcpus=4 -numa node,cpus=0-3

* Incomplete, with warnings:

  $ qemu-system-x86_64 -smp 2,maxcpus=4 -numa node,cpus=0
  qemu-system-x86_64: warning: CPU(s) not present in any NUMA nodes: 1 2 3
  qemu-system-x86_64: warning: All CPU(s) up to maxcpus should be described in NUMA config

  $ qemu-system-x86_64 -smp 2,maxcpus=4 -numa node,cpus=0-2
  qemu-system-x86_64: warning: CPU(s) not present in any NUMA nodes: 3
  qemu-system-x86_64: warning: All CPU(s) up to maxcpus should be described in NUMA config

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
v1 -> v2: (no changes)

v2 -> v3:
 * Use enumerate_cpus() and error_report() for error message
 * Simplify logic using bitmap_full()

v3 -> v4:
 * Clarify error message, mention that all CPUs up to
   maxcpus need to be described in NUMA config

v4 -> v5:
 * Commit log update, to make problem description clearer
This commit is contained in:
Eduardo Habkost 2015-02-09 17:35:04 -02:00
parent fb43b73b92
commit 549fc54b8c
1 changed files with 10 additions and 0 deletions
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10
numa.c
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@ -200,6 +200,16 @@ static void validate_numa_cpus(void)
bitmap_or(seen_cpus, seen_cpus,
numa_info[i].node_cpu, MAX_CPUMASK_BITS);
}
if (!bitmap_full(seen_cpus, max_cpus)) {
char *msg;
bitmap_complement(seen_cpus, seen_cpus, max_cpus);
msg = enumerate_cpus(seen_cpus, max_cpus);
error_report("warning: CPU(s) not present in any NUMA nodes: %s", msg);
error_report("warning: All CPU(s) up to maxcpus should be described "
"in NUMA config");
g_free(msg);
}
}
void parse_numa_opts(MachineClass *mc)