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Re: [libvirt] [PATCH v2.1 02/21] Introduce the function virCgroupMoveTask



On Tue, Aug 21, 2012 at 05:18:25PM +0800, Hu Tao wrote:
> Introduce a new API to move tasks of one controller from a cgroup to another cgroup
> 
> Signed-off-by: Wen Congyang <wency cn fujitsu com>
> Signed-off-by: Tang Chen <tangchen cn fujitsu com>
> Signed-off-by: Hu Tao <hutao cn fujitsu com>
> ---
>  src/libvirt_private.syms |    2 +
>  src/util/cgroup.c        |  110 ++++++++++++++++++++++++++++++++++++++++++++++
>  src/util/cgroup.h        |    8 ++++
>  3 files changed, 120 insertions(+)
> 
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 6e834fe..0b0a70d 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -60,6 +60,7 @@ virCapabilitiesSetMacPrefix;
>  
>  # cgroup.h
>  virCgroupAddTask;
> +virCgroupAddTaskController;
>  virCgroupAllowDevice;
>  virCgroupAllowDeviceMajor;
>  virCgroupAllowDevicePath;
> @@ -91,6 +92,7 @@ virCgroupKill;
>  virCgroupKillPainfully;
>  virCgroupKillRecursive;
>  virCgroupMounted;
> +virCgroupMoveTask;
>  virCgroupPathOfController;
>  virCgroupRemove;
>  virCgroupSetBlkioDeviceWeight;
> diff --git a/src/util/cgroup.c b/src/util/cgroup.c
> index 169b56a..24e08b4 100644
> --- a/src/util/cgroup.c
> +++ b/src/util/cgroup.c
> @@ -802,6 +802,116 @@ int virCgroupAddTask(virCgroupPtr group, pid_t pid)
>      return rc;
>  }
>  
> +/**
> + * virCgroupAddTaskController:
> + *
> + * @group: The cgroup to add a task to
> + * @pid: The pid of the task to add
> + * @controller: The cgroup controller to be operated on
> + *
> + * Returns: 0 on success or -errno on failure
> + */
> +int virCgroupAddTaskController(virCgroupPtr group, pid_t pid, int controller)
> +{
> +    if (controller < VIR_CGROUP_CONTROLLER_CPU ||
> +        controller > VIR_CGROUP_CONTROLLER_BLKIO)
> +        return -EINVAL;

This conditional should really be

  if (controller < 0 || controller >= VIR_CGROUP_CONTROLLER_LAST)

> +
> +    if (!group->controllers[controller].mountPoint)
> +        return -EINVAL;
> +
> +    return virCgroupSetValueU64(group, controller, "tasks",
> +                                (unsigned long long)pid);
> +}
> +
> +
> +static int virCgroupAddTaskStrController(virCgroupPtr group,
> +                                        const char *pidstr,
> +                                        int controller)
> +{
> +    char *str = NULL, *cur = NULL, *next = NULL;
> +    unsigned long long p = 0;
> +    int rc = 0;
> +    char *endp;
> +
> +    if (virAsprintf(&str, "%s", pidstr) < 0)
> +        return -1;
> +
> +    cur = str;
> +    while (*cur != '\0') {
> +        rc = virStrToLong_ull(cur, &endp, 10, &p);
> +        if (rc != 0)
> +            goto cleanup;
> +
> +        rc = virCgroupAddTaskController(group, p, controller);
> +        if (rc != 0)
> +            goto cleanup;
> +
> +        next = strchr(cur, '\n');
> +        if (next) {
> +            cur = next + 1;
> +            *next = '\0';
> +        } else {
> +            break;
> +        }
> +    }
> +
> +cleanup:
> +    VIR_FREE(str);
> +    return rc;
> +}
> +
> +/**
> + * virCgroupMoveTask:
> + *
> + * @src_group: The source cgroup where all tasks are removed from
> + * @dest_group: The destination where all tasks are added to
> + * @controller: The cgroup controller to be operated on
> + *
> + * Returns: 0 on success or -errno on failure
> + */
> +int virCgroupMoveTask(virCgroupPtr src_group, virCgroupPtr dest_group,
> +                      int controller)
> +{
> +    int rc = 0, err = 0;
> +    char *content = NULL;
> +
> +    if (controller < VIR_CGROUP_CONTROLLER_CPU ||
> +        controller > VIR_CGROUP_CONTROLLER_BLKIO)
> +        return -EINVAL;
> +
> +    if (!src_group->controllers[controller].mountPoint ||
> +        !dest_group->controllers[controller].mountPoint) {
> +        VIR_WARN("no vm cgroup in controller %d", controller);
> +        return 0;
> +    }
> +
> +    rc = virCgroupGetValueStr(src_group, controller, "tasks", &content);
> +    if (rc != 0)
> +        return rc;
> +
> +    rc = virCgroupAddTaskStrController(dest_group, content, controller);
> +    if (rc != 0)
> +        goto cleanup;
> +
> +    VIR_FREE(content);
> +
> +    return 0;
> +
> +cleanup:
> +    /*
> +     * We don't need to recover dest_cgroup because cgroup will make sure
> +     * that one task only resides in one cgroup of the same controller.
> +     */
> +    err = virCgroupAddTaskStrController(src_group, content, controller);
> +    if (err != 0)
> +        VIR_ERROR(_("Cannot recover cgroup %s from %s"),
> +                  src_group->controllers[controller].mountPoint,
> +                  dest_group->controllers[controller].mountPoint);
> +    VIR_FREE(content);
> +
> +    return rc;
> +}
>  
>  /**
>   * virCgroupForDriver:
> diff --git a/src/util/cgroup.h b/src/util/cgroup.h
> index 9f803a5..727e536 100644
> --- a/src/util/cgroup.h
> +++ b/src/util/cgroup.h
> @@ -70,6 +70,14 @@ int virCgroupPathOfController(virCgroupPtr group,
>  
>  int virCgroupAddTask(virCgroupPtr group, pid_t pid);
>  
> +int virCgroupAddTaskController(virCgroupPtr group,
> +                               pid_t pid,
> +                               int controller);
> +
> +int virCgroupMoveTask(virCgroupPtr src_group,
> +                      virCgroupPtr dest_group,
> +                      int controller);
> +
>  int virCgroupSetBlkioWeight(virCgroupPtr group, unsigned int weight);
>  int virCgroupGetBlkioWeight(virCgroupPtr group, unsigned int *weight);

ACK


Daniel
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