[libvirt] [RFC PATCH 2/2] Routines to parse <numa> ... </numa>

Daniel P. Berrange berrange at redhat.com
Thu Oct 13 11:50:00 UTC 2011


On Mon, Oct 03, 2011 at 03:31:35PM +0530, Bharata B Rao wrote:
> Routines to parse <numa> ... </numa>
> 
> From: Bharata B Rao <bharata at linux.vnet.ibm.com>
> 
> This patch adds routines to parse guest numa
> XML configuration for qemu.
> 
> Signed-off-by: Bharata B Rao <bharata at linux.vnet.ibm.com>
> ---
> 
>  src/conf/cpu_conf.c     |   48 ++++++++++++++++++++++++
>  src/conf/cpu_conf.h     |   11 ++++++
>  src/qemu/qemu_command.c |   94 +++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 153 insertions(+), 0 deletions(-)
> 
> 
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index a13ba71..5b4345e 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -3153,6 +3153,97 @@ qemuBuildSmpArgStr(const virDomainDefPtr def,
>      return virBufferContentAndReset(&buf);
>  }
>  
> +static char *
> +virParseNodeCPUs(char *cpumask)

This is a rather misleading name, since it is really formatting
the argument value. Can you rename this to qemuBuildNumaCPUArgStr

> +{
> +    int i, first, last, ret;
> +    char *cpus, *ptr;
> +    int cpuSet = 0;
> +    int remaining = 128;
> +
> +    if (VIR_ALLOC_N(cpus, remaining) < 0)
> +        return NULL;
> +
> +    ptr = cpus;
> +
> +    for (i = 0; i < VIR_DOMAIN_CPUMASK_LEN; i++) {
> +        if (cpumask[i]) {
> +            if (cpuSet)
> +                last = i;
> +            else {
> +                first = last = i;
> +                cpuSet = 1;
> +            }
> +        } else {
> +            if (!cpuSet)
> +                continue;
> +            if (first == last)
> +                ret = snprintf(ptr, remaining, "%d,", first);
> +            else
> +                ret = snprintf(ptr, remaining, "%d-%d,", first, last);
> +            if (ret > remaining)
> +                goto error;
> +            ptr += ret;
> +            remaining -= ret;
> +            cpuSet = 0;
> +	}
> +    }
> +
> +    if (cpuSet) {
> +        if (first == last)
> +            ret = snprintf(ptr, remaining, "%d,", first);
> +        else
> +            ret = snprintf(ptr, remaining, "%d-%d,", first, last);
> +        if (ret > remaining)
> +            goto error;
> +    }
> +
> +    /* Remove the trailing comma */
> +    *(--ptr) = '\0';
> +    return cpus;
> +
> +error:
> +    VIR_FREE(cpus);
> +    return NULL;

Using VIR_ALLOC_N + snprintf here is not desirable, when you
already have a nice  virBufferPtr object in the call that you
could use.  Just pass the virBufferPtr straight into this
method.

> +}
> +
> +static int
> +qemuBuildNumaArgStr(const virDomainDefPtr def, virCommandPtr cmd)
> +{
> +    int i;
> +    char *cpus, *node;
> +    virBuffer buf = VIR_BUFFER_INITIALIZER;
> +
> +    for (i = 0; i < def->cpu->nnodes; i++) {
> +        virCommandAddArg(cmd, "-numa");
> +        virBufferAsprintf(&buf, "%s", "node");
> +        virBufferAsprintf(&buf, ",nodeid=%d", def->cpu->nodes[i].nodeid);
> +
> +        cpus = virParseNodeCPUs(def->cpu->nodes[i].cpumask);
> +        if (!cpus)
> +            goto error;
> +
> +        virBufferAsprintf(&buf, ",cpus=%s", cpus);
> +        virBufferAsprintf(&buf, ",mems=%d", def->cpu->nodes[i].mem);
> +
> +        if (virBufferError(&buf)) {
> +            VIR_FREE(cpus);
> +            goto error;
> +        }
> +
> +        node = virBufferContentAndReset(&buf);
> +        virCommandAddArg(cmd, node);
> +
> +        VIR_FREE(cpus);
> +        VIR_FREE(node);
> +    }
> +    return 0;
> +
> +error:
> +    virBufferFreeAndReset(&buf);
> +    virReportOOMError();
> +    return -1;
> +}
>  
>  /*
>   * Constructs a argv suitable for launching qemu with config defined
> @@ -3319,6 +3410,9 @@ qemuBuildCommandLine(virConnectPtr conn,
>      virCommandAddArg(cmd, smp);
>      VIR_FREE(smp);
>  
> +    if (def->cpu->nnodes && qemuBuildNumaArgStr(def, cmd))
> +        goto error;
> +
>      if (qemuCapsGet(qemuCaps, QEMU_CAPS_NAME)) {
>          virCommandAddArg(cmd, "-name");
>          if (driver->setProcessName &&

Looks fine code wise. For the future iterations, it would be good to
change the split of patches slightly

  - Patch 1 for XML bits:  cpu_conf.c, cpu_conf.h, and docs/schemas/domain.rn
  - Patch 2 for qemu_command.c, tests/qemuxml2argvtest.c

Regards,
Daniel
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