[libvirt] [PATCH] virsh nodecpustats returns incorrect stats of cpu on Linux when the number of online cpu exceed 9.

Ján Tomko jtomko at redhat.com
Thu Jan 16 13:18:48 UTC 2014


On 01/16/2014 09:13 AM, mars at linux.vnet.ibm.com wrote:
> From: Bing Bu Cao <mars at linux.vnet.ibm.com>
> 
> To retrieve node cpu statistics on Linux system, the
> linuxNodeGetCPUstats function simply uses STRPREFIX() to match the
> cpuid with the cpuid read from /proc/stat, it will cause
> obvious error.
> 
> For example:
> 'virsh nodecpustats 1' will display stats of cpu1* if the latter is online and cpu1 is offline.
> 
> This patch fixes this bug.
> 
> Signed-off-by: Bing Bu Cao <mars at linux.vnet.ibm.com>
> ---
>  src/nodeinfo.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 

The size of the cpu_header should also be enlarged by one, for cpu numbers
with the same number of digits as INT_MAX has :)

> diff --git a/src/nodeinfo.c b/src/nodeinfo.c
> index 05bc038..cba2fc1 100644
> --- a/src/nodeinfo.c
> +++ b/src/nodeinfo.c
> @@ -708,9 +708,9 @@ linuxNodeGetCPUStats(FILE *procstat,
>      }
>  
>      if (cpuNum == VIR_NODE_CPU_STATS_ALL_CPUS) {
> -        strcpy(cpu_header, "cpu");
> +        strcpy(cpu_header, "cpu ");
>      } else {
> -        snprintf(cpu_header, sizeof(cpu_header), "cpu%d", cpuNum);
> +        snprintf(cpu_header, sizeof(cpu_header), "cpu%d ", cpuNum);
>      }
>  
>      while (fgets(line, sizeof(line), procstat) != NULL) {
> 

ACK, but this should probably be squashed together in one commit along with
the test addition.

Jan

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