Re: [Qemu-devel] [PATCH 2/2] Add monitor command mem-nodes

[Eduardo Habkost <ehabkost@redhat.com>]

On Wed, Jun 05, 2013 at 11:58:25AM +0800, Wanlong Gao wrote:
> Add monitor command mem-nodes to show the huge mapped
> memory nodes locations.
> 

This is for machine consumption, so we need a QMP command.

> (qemu) info mem-nodes
> /proc/14132/fd/13: 00002aaaaac00000-00002aaaeac00000: node0
> /proc/14132/fd/13: 00002aaaeac00000-00002aab2ac00000: node1
> /proc/14132/fd/14: 00002aab2ac00000-00002aab2b000000: node0
> /proc/14132/fd/14: 00002aab2b000000-00002aab2b400000: node1

Are node0/node1 _host_ nodes?

How do I know what's the _guest_ address/node corresponding to each
file/range above?

What I am really looking for is:

 * The correspondence between guest (virtual) NUMA nodes and guest
   physical address ranges (it could be provided by the QMP version of
   "info numa")
 * The correspondence between guest physical address ranges and ranges
   inside the mapped files (so external tools could set the policy on
   those files instead of requiring QEMU to set it directly)

I understand that your use case may require additional information and
additional interfaces. But if we provide the information above we will
allow external components set the policy on the hugetlbfs files before
we add new interfaces required for your use case.

Also, what about making it conditional to OSes where we really know
"/proc/<pid>/fd/<fd>" is available?


> 
> Refer to the proposal of Eduardo and Daniel.
> http://article.gmane.org/gmane.comp.emulators.kvm.devel/93476

> 
> Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
> ---
>  monitor.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 45 insertions(+)
> 
> diff --git a/monitor.c b/monitor.c
> index eefc7f0..85c865f 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -74,6 +74,10 @@
>  #endif
>  #include "hw/lm32/lm32_pic.h"
>  
> +#if defined(CONFIG_NUMA)
> +#include <numaif.h>
> +#endif
> +
>  //#define DEBUG
>  //#define DEBUG_COMPLETION
>  
> @@ -1759,6 +1763,38 @@ static void mem_info(Monitor *mon, const QDict *qdict)
>  }
>  #endif
>  
> +#if defined(CONFIG_NUMA)
> +static void mem_nodes(Monitor *mon, const QDict *qdict)
> +{
> +    RAMBlock *block;
> +    int prevnode, node;
> +    unsigned long long c, start, area;
> +    int fd;
> +    int pid = getpid();
> +    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
> +        if (!(fd = block->fd))
> +            continue;
> +        prevnode = -1;
> +        start = 0;
> +        area = (unsigned long long)block->host;
> +        for (c = 0; c < block->length; c += TARGET_PAGE_SIZE) {
> +            if (get_mempolicy(&node, NULL, 0, c + block->host,
> +                              MPOL_F_ADDR | MPOL_F_NODE) < 0)
> +                continue;
> +            if (node == prevnode)
> +                continue;
> +            if (prevnode != -1)
> +                monitor_printf(mon, "/proc/%d/fd/%d: %016Lx-%016Lx: node%d\n",
> +                               pid, fd, start + area, c + area, prevnode);
> +            prevnode = node;
> +            start = c;
> +         }
> +         monitor_printf(mon, "/proc/%d/fd/%d: %016Lx-%016Lx: node%d\n",
> +                        pid, fd, start + area, c + area, prevnode);
> +    }
> +}
> +#endif
> +
>  #if defined(TARGET_SH4)
>  
>  static void print_tlb(Monitor *mon, int idx, tlb_t *tlb)
> @@ -2567,6 +2603,15 @@ static mon_cmd_t info_cmds[] = {
>          .mhandler.cmd = mem_info,
>      },
>  #endif
> +#if defined(CONFIG_NUMA)
> +    {
> +        .name       = "mem-nodes",
> +        .args_type  = "",
> +        .params     = "",
> +        .help       = "show the huge mapped memory nodes location",
> +        .mhandler.cmd = mem_nodes,
> +    },
> +#endif
>      {
>          .name       = "mtree",
>          .args_type  = "",
> -- 
> 1.8.3.rc2.10.g0c2b1cf
> 

-- 
Eduardo