[libvirt] [PATCH 3/3] qemu: Implement blkio tunable XML configuration and parsing.

[Daniel P. Berrange]

On Sun, Jan 23, 2011 at 02:19:44PM +0800, Gui Jianfeng wrote:
> Implement blkio tunable XML configuration and parsing.
> 
> Signed-off-by: Gui Jianfeng <guijianfeng at cn.fujitsu.com>
> ---
>  src/conf/domain_conf.c |   17 ++++++++++++++++-
>  src/conf/domain_conf.h |    4 ++++
>  src/qemu/qemu_cgroup.c |   16 +++++++++++++++-
>  src/qemu/qemu_conf.c   |    3 ++-
>  4 files changed, 37 insertions(+), 3 deletions(-)

This needs to also update docs/schemas/domain.rng
and ideally add a new test case + example datafile
for tests/qemuxml2xmltest.c

> 
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 645767e..a05ada5 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -4810,7 +4810,7 @@ static virDomainDefPtr virDomainDefParseXML(virCapsPtr caps,
>  {
>      xmlNodePtr *nodes = NULL, node = NULL;
>      char *tmp = NULL;
> -    int i, n;
> +    int i, n, w;
>      long id = -1;
>      virDomainDefPtr def;
>      unsigned long count;
> @@ -4887,6 +4887,13 @@ static virDomainDefPtr virDomainDefParseXML(virCapsPtr caps,
>      if (node)
>          def->mem.hugepage_backed = 1;
>  
> +    /* Extract blkio cgroup tunables */
> +    w = virXPathULong("string(./blkiotune/weight)", ctxt,
> +                      &def->blkio.weight);
> +    if (w < 0 || def->blkio.weight > 1000 || def->blkio.weight < 100)
> +        virDomainReportError(VIR_ERR_XML_ERROR, "%s",
> +                             _("I/O weight should fall in [100, 1000]"));
> +

The virDomainDefParseXML method should only do syntax validation.
Semantic validation should be left to the hypervisor drivers.

>      /* Extract other memory tunables */
>      if (virXPathULong("string(./memtune/hard_limit)", ctxt,
>                        &def->mem.hard_limit) < 0)
> @@ -7289,6 +7296,14 @@ char *virDomainDefFormat(virDomainDefPtr def,
>      virBufferVSprintf(&buf, "  <currentMemory>%lu</currentMemory>\n",
>                        def->mem.cur_balloon);
>  
> +    /* add blkiotune only if there are any */
> +    if (def->blkio.weight) {
> +        virBufferVSprintf(&buf, "  <blkiotune>\n");
> +        virBufferVSprintf(&buf, "    <weight>%lu</weight>\n",
> +                          def->blkio.weight);
> +        virBufferVSprintf(&buf, "  </blkiotune>\n");
> +    }
> +
>      /* add memtune only if there are any */
>      if (def->mem.hard_limit || def->mem.soft_limit || def->mem.min_guarantee ||
>          def->mem.swap_hard_limit)
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index cf7bdc0..b117869 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -969,6 +969,10 @@ struct _virDomainDef {
>      char *description;
>  
>      struct {
> +        unsigned long weight;
> +    } blkio;
> +
> +    struct {
>          unsigned long max_balloon;
>          unsigned long cur_balloon;
>          unsigned long hugepage_backed;
> diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c
> index e5536c0..a3e8e6a 100644
> --- a/src/qemu/qemu_cgroup.c
> +++ b/src/qemu/qemu_cgroup.c
> @@ -54,7 +54,6 @@ int qemuCgroupControllerActive(struct qemud_driver *driver,
>      return 0;
>  }
>  
> -
>  int qemuSetupDiskPathAllow(virDomainDiskDefPtr disk ATTRIBUTE_UNUSED,
>                             const char *path,
>                             size_t depth ATTRIBUTE_UNUSED,
> @@ -270,6 +269,21 @@ int qemuSetupCgroup(struct qemud_driver *driver,
>          }
>      }
>  
> +    if (qemuCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_BLKIO)) {
> +        if (vm->def->blkio.weight != 0) {
> +            rc = virCgroupSetWeight(cgroup, vm->def->blkio.weight);
> +            if(rc != 0) {
> +                virReportSystemError(-rc,
> +                                     _("Unable to set io weight for domain %s"),
> +                                     vm->def->name);
> +                goto cleanup;
> +            }
> +        }
> +    } else {
> +        VIR_WARN("Blkio cgroup is disabled in qemu configuration file: %s",
> +                 vm->def->name);
> +    }

I think it is probably worth raising a real error here

    qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                    _("Block I/O tuning is not available on this host"));

Regards,
Daniel