Re: [PATCH v4 07/13] Implement driver interface domainGetMemoryParamters for QEmu

[Daniel Veillard <veillard@xxxxxxxxxx>]

On Fri, Oct 08, 2010 at 05:45:55PM +0530, Nikunj A. Dadhania wrote:
> From: Nikunj A. Dadhania <nikunj@xxxxxxxxxxxxxxxxxx>
> 
> V4:
> * prototype change: add unsigned int flags
> 
> Driver interface for getting memory parameters, eg. hard_limit, soft_limit and
> swap_hard_limit.
> 
> Signed-off-by: Nikunj A. Dadhania <nikunj@xxxxxxxxxxxxxxxxxx>
> ---
>  src/qemu/qemu_driver.c |  120 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 119 insertions(+), 1 deletions(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 471db39..8eaa762 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -9458,6 +9458,124 @@ cleanup:
>      return ret;
>  }

  same things about crashing if the arguments are invalid

> +    if ((*nparams) == 0) {
> +        /* Current number of memory parameters supported by cgroups is 3
> +         * FIXME: Magic number, need to see where should this go
> +         */
> +        *nparams = 3;
> +        ret = 0;
> +        goto cleanup;
> +    }
> +    
> +    if ((*nparams) != 3) {

  using QEMU_NB_MEM_PARAM instead of the raw 3 value c.f. previous patch
  comment

> +        qemuReportError(VIR_ERR_INVALID_ARG,
> +                        "%s", _("Invalid parameter count"));
> +        goto cleanup;
> +    }

  okay, this mean the application must always call with 0 first to get
  the exact value or this will break, fine but probably need to be made
  more clear from the description in libvirt.c .... TODO

> +    if (virCgroupForDomain(driver->cgroup, vm->def->name, &group, 0) != 0) {
> +        qemuReportError(VIR_ERR_INTERNAL_ERROR,
> +                        _("cannot find cgroup for domain %s"), vm->def->name);
> +        goto cleanup;
> +    }
> +
> +    for (i = 0; i < *nparams; i++) {
> +        virMemoryParameterPtr param = &params[i];
> +        val = 0;
> +        param->value.ul = 0;
> +        param->type = VIR_DOMAIN_MEMORY_FIELD_ULLONG;
> +
> +        switch(i) {
> +        case 0: /* fill memory hard limit here */
> +            rc = virCgroupGetMemoryHardLimit(group, &val);
> +            if (rc != 0) {
> +                virReportSystemError(-rc, "%s",
> +                                     _("unable to get memory hard limit"));
> +                continue;
> +            }
> +            if (virStrcpyStatic(param->field, VIR_DOMAIN_MEMORY_HARD_LIMIT) == NULL) {
> +                qemuReportError(VIR_ERR_INTERNAL_ERROR,
> +                                "%s", _("Field memory hard limit too long for destination"));
> +                continue;
> +            }
> +            param->value.ul = val;
> +            break;
> +
> +        case 1: /* fill memory soft limit here */
> +            rc = virCgroupGetMemorySoftLimit(group, &val);
> +            if (rc != 0) {
> +                virReportSystemError(-rc, "%s",
> +                                     _("unable to get memory soft limit"));
> +                continue;
> +            }
> +            if (virStrcpyStatic(param->field, VIR_DOMAIN_MEMORY_SOFT_LIMIT) == NULL) {
> +                qemuReportError(VIR_ERR_INTERNAL_ERROR,
> +                                "%s", _("Field memory soft limit too long for destination"));
> +                continue;
> +            }
> +            param->value.ul = val;
> +            break;
> +           
> +        case 2: /* fill swap hard limit here */
> +            rc = virCgroupGetSwapHardLimit(group, &val);
> +            if (rc != 0) {
> +                virReportSystemError(-rc, "%s",
> +                                     _("unable to get swap hard limit"));
> +                continue;
> +            }
> +            if (virStrcpyStatic(param->field, VIR_DOMAIN_SWAP_HARD_LIMIT) == NULL) {
> +                qemuReportError(VIR_ERR_INTERNAL_ERROR,
> +                                "%s", _("Field swap hard limit too long for destination"));
> +                continue;
> +            }
> +            param->value.ul = val;
> +            break;
> +            
> +        default:
> +            break;
> +            /* should not hit here */
> +        }
> +    }

  Okay, I'm not sure we actually need a loop here, but it may help
  refactoring...
I'm still having a problem with the code ignoring any error occuring in
the loop, and fixing this in the same way. If there is an error the
application *must* learn about it instead of trusting uninitialized
memory as being data !
Maybe a memset is in order actually before entering that loop to avoid
edge case problems... TODO too

> +    ret = 0;
> +
> +cleanup:
> +    if (group)
> +        virCgroupFree(&group);
> +    if (vm)
> +        virDomainObjUnlock(vm);
> +    qemuDriverUnlock(driver);
> +    return ret;
> +}
> +
>  static int qemuSetSchedulerParameters(virDomainPtr dom,
>                                        virSchedParameterPtr params,
>                                        int nparams)
> @@ -12804,7 +12922,7 @@ static virDriver qemuDriver = {
>      qemuDomainSnapshotDelete, /* domainSnapshotDelete */
>      qemuDomainMonitorCommand, /* qemuDomainMonitorCommand */
>      qemuDomainSetMemoryParameters, /* domainSetMemoryParameters */
> -    NULL, /* domainGetMemoryParameters */
> +    qemuDomainGetMemoryParameters, /* domainGetMemoryParameters */
>  };

  Okay, once heavilly patched as described, ACK, I commited this to my tree,

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel@xxxxxxxxxxxx  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/

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