Re: [Qemu-devel] [PATCH V4 08/10] NUMA: add qmp command set-mpol to set memory policy for NUMA node

[Luiz Capitulino <lcapitulino@redhat.com>]

On Thu, 4 Jul 2013 17:53:15 +0800
Wanlong Gao <gaowanlong@cn.fujitsu.com> wrote:

> The QMP command let it be able to set node's memory policy
> through the QMP protocol. The qmp-shell command is like:
>     set-mpol nodeid=0 mem-policy=membind mem-hostnode=0-1
> 
> Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
> ---
>  cpus.c           | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  qapi-schema.json | 15 +++++++++++++++
>  qmp-commands.hx  | 35 +++++++++++++++++++++++++++++++++++
>  3 files changed, 104 insertions(+)
> 
> diff --git a/cpus.c b/cpus.c
> index 7240de7..ff42b9d 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -1417,3 +1417,57 @@ void qmp_inject_nmi(Error **errp)
>      error_set(errp, QERR_UNSUPPORTED);
>  #endif
>  }
> +
> +void qmp_set_mpol(int64_t nodeid, bool has_mpol, const char *mpol,
> +                  bool has_hostnode, const char *hostnode, Error **errp)
> +{
> +    unsigned int flags;
> +    DECLARE_BITMAP(host_mem, MAX_CPUMASK_BITS);
> +
> +    if (nodeid >= nb_numa_nodes) {
> +        error_setg(errp, "Only has '%d' NUMA nodes", nb_numa_nodes);
> +        return;
> +    }
> +
> +    bitmap_copy(host_mem, numa_info[nodeid].host_mem, MAX_CPUMASK_BITS);
> +    flags = numa_info[nodeid].flags;
> +
> +    numa_info[nodeid].flags = NODE_HOST_NONE;
> +    bitmap_zero(numa_info[nodeid].host_mem, MAX_CPUMASK_BITS);
> +
> +    if (!has_mpol) {
> +        if (set_node_mpol(nodeid) == -1) {
> +            error_setg(errp, "Failed to set memory policy for node%lu", nodeid);
> +            goto error;
> +        }
> +        return;
> +    }
> +
> +    numa_node_parse_mpol(nodeid, mpol, errp);
> +    if (error_is_set(errp)) {
> +        goto error;
> +    }
> +
> +    if (!has_hostnode) {
> +        bitmap_fill(numa_info[nodeid].host_mem, MAX_CPUMASK_BITS);
> +    }
> +
> +    if (hostnode) {
> +        numa_node_parse_hostnode(nodeid, hostnode, errp);
> +        if (error_is_set(errp)) {
> +            goto error;
> +        }
> +    }
> +
> +    if (set_node_mpol(nodeid) == -1) {
> +        error_setg(errp, "Failed to set memory policy for node%lu", nodeid);
> +        goto error;
> +    }
> +
> +    return;
> +
> +error:
> +    bitmap_copy(numa_info[nodeid].host_mem, host_mem, MAX_CPUMASK_BITS);
> +    numa_info[nodeid].flags = flags;
> +    return;
> +}
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 5c32528..0870da2 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -3712,3 +3712,18 @@
>              '*cpuid-input-ecx': 'int',
>              'cpuid-register': 'X86CPURegister32',
>              'features': 'int' } }
> +
> +# @set-mpol:
> +#
> +# Set the host memory binding policy for guest NUMA node.
> +#
> +# @nodeid: The node ID of guest NUMA node to set memory policy to.
> +#
> +# @mem-policy: The memory policy string to set.

Shouldn't this be an enum? Also, optional members have a leading '#optional'
string and if a default value is used it should be documented.

> +#
> +# @mem-hostnode: The host node or node range for memory policy.

It doesn't seem appropriate to use a string here. Maybe we could
use a list with only to values (like [0,2] for 0-2) or maybe a
list of nodes if that makes sense (like [0,1,2]).

> +#
> +# Since: 1.6.0
> +##
> +{ 'command': 'set-mpol', 'data': {'nodeid': 'int', '*mem-policy': 'str',
> +                                  '*mem-hostnode': 'str'} }
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index 362f0e1..ccab51b 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -3043,3 +3043,38 @@ Example:
>  <- { "return": {} }
>  
>  EQMP
> +
> +    {
> +        .name      = "set-mpol",
> +        .args_type = "nodeid:i,mem-policy:s?,mem-hostnode:s?",
> +        .help      = "Set the host memory binding policy for guest NUMA node",
> +        .mhandler.cmd_new = qmp_marshal_input_set_mpol,
> +    },
> +
> +SQMP
> +set-mpol
> +------
> +
> +Set the host memory binding policy for guest NUMA node
> +
> +Arguments:
> +
> +- "nodeid": The nodeid of guest NUMA node to set memory policy to.
> +            (json-int)
> +- "mem-policy": The memory policy string to set.
> +                (json-string, optional)
> +- "mem-hostnode": The host nodes contained to mpol.
> +                  (json-string, optional)
> +
> +Example:
> +
> +-> { "execute": "set-mpol", "arguments": { "nodeid": 0, "mem-policy": "membind",
> +                                           "mem-hostnode": "0-1" }}
> +<- { "return": {} }
> +
> +Notes:
> +    1. If "mem-policy" is not set, the memory policy of this "nodeid" will be set
> +       to "default".
> +    2. If "mem-hostnode" is not set, the node mask of this "mpol" will be set
> +       to "all".
> +EQMP