From 549fc54b8cfe16a475d8f6b8f838e53b45452b4a Mon Sep 17 00:00:00 2001 From: Eduardo Habkost Date: Mon, 9 Feb 2015 17:35:04 -0200 Subject: [PATCH] numa: Print warning if no node is assigned to a CPU 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 --- 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 --- numa.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/numa.c b/numa.c index fe74e1eeaf..c975fb2682 100644 --- a/numa.c +++ b/numa.c @@ -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)