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Re: [libvirt] [PATCH 4/5] capabilities: Switch CPU data in NUMA topology to a struct



On 01/19/2013 12:06 AM, Peter Krempa wrote:
> This will allow storing additional topology data in the NUMA topology
> definition.
> 
> This patch changes the storage type and fixes fallback of the change
> across the drivers using it.
> 
> This patch also changes semantics of adding new NUMA cell information.
> Until now the data were re-allocated and copied to the topology
> definition. This patch changes the addition function to steal the
> pointer to a pre-allocated structure to simplify the code.
> ---
>  src/conf/capabilities.c | 29 ++++++++++++++++++-----------
>  src/conf/capabilities.h | 14 ++++++++++++--
>  src/nodeinfo.c          | 22 ++++++++++++----------
>  src/qemu/qemu_process.c |  2 +-
>  src/test/test_driver.c  | 15 ++++++++++++---
>  src/xen/xend_internal.c | 24 +++++++++++++-----------
>  6 files changed, 68 insertions(+), 38 deletions(-)
> 

[...]

> diff --git a/src/conf/capabilities.h b/src/conf/capabilities.h
> index 19b99c6..124d8c1 100644
> --- a/src/conf/capabilities.h
> +++ b/src/conf/capabilities.h
> @@ -84,12 +84,21 @@ struct _virCapsGuest {
>      virCapsGuestFeaturePtr *features;
>  };
> 
> +typedef struct _virCapsHostNUMACellCPU virCapsHostNUMACellCPU;
> +typedef virCapsHostNUMACellCPU *virCapsHostNUMACellCPUPtr;
> +struct _virCapsHostNUMACellCPU {
> +    int id;
> +    int socket_id;
> +    int core_id;
> +    char *siblings_list;

We don't actually need this for anything right now, but it would be nice
to have it stored in virBitmap in case we'll want to work with it in the
future.

[...]

> diff --git a/src/nodeinfo.c b/src/nodeinfo.c
> index 477104f..dffe7d1 100644
> --- a/src/nodeinfo.c
> +++ b/src/nodeinfo.c
> @@ -79,9 +79,11 @@ freebsdNodeGetCPUCount(void)
>  #ifdef __linux__
>  # define CPUINFO_PATH "/proc/cpuinfo"
>  # define SYSFS_SYSTEM_PATH "/sys/devices/system"
> +# define SYSFS_CPU_PATH SYSFS_SYSTEM_PATH"/cpu"

s/PATH"/PATH "/

>  # define PROCSTAT_PATH "/proc/stat"
>  # define MEMINFO_PATH "/proc/meminfo"
>  # define SYSFS_MEMORY_SHARED_PATH "/sys/kernel/mm/ksm"
> +# define SYSFS_THREAD_SIBLINGS_LIST_LENGHT_MAX 1024
> 
>  # define LINUX_NB_CPU_STATS 4
>  # define LINUX_NB_MEMORY_STATS_ALL 4
> @@ -1476,9 +1478,10 @@ nodeCapsInitNUMA(virCapsPtr caps)
>      int n;
>      unsigned long *mask = NULL;
>      unsigned long *allonesmask = NULL;
> -    int *cpus = NULL;
> +    virCapsHostNUMACellCPUPtr cpus = NULL;
>      int ret = -1;
>      int max_n_cpus = NUMA_MAX_N_CPUS;
> +    int ncpus = 0;
> 
>      if (numa_available() < 0)
>          return 0;
> @@ -1492,7 +1495,6 @@ nodeCapsInitNUMA(virCapsPtr caps)
> 
>      for (n = 0 ; n <= numa_max_node() ; n++) {
>          int i;
> -        int ncpus;
>          /* The first time this returns -1, ENOENT if node doesn't exist... */
>          if (numa_node_to_cpus(n, mask, mask_n_bytes) < 0) {
>              VIR_WARN("NUMA topology for cell %d of %d not available, ignoring",
> @@ -1515,21 +1517,21 @@ nodeCapsInitNUMA(virCapsPtr caps)
> 
>          for (ncpus = 0, i = 0 ; i < max_n_cpus ; i++)
>              if (MASK_CPU_ISSET(mask, i))
> -                cpus[ncpus++] = i;
> +                cpus[ncpus++].id = i;
> 
> -        if (virCapabilitiesAddHostNUMACell(caps,
> -                                           n,
> -                                           ncpus,
> -                                           cpus) < 0)
> +        if (virCapabilitiesAddHostNUMACell(caps, n, ncpus, cpus) < 0)
>              goto cleanup;
> -
> -        VIR_FREE(cpus);
> +        cpus = NULL;

I generally don't like stealing pointers because of similar
contraptions.  Even though it is clear from memory allocation POV and it
saves a lot of allocations in this case, it's a bit harder to read IMHO.

Being the devil's advocate, I must say I'd be nice to have the tests for
this since you've started modifying the test driver.  Also documentation
for all the new information should be added into
'docs/formatcaps.html.in' with some explanation.

Xen part of this patch looks OK, although I don't have any XEN machine
to try it on.

Because this and [PATCH 5/5] both require [PATCH 3/5] to be in, I'm
cond-ACKing this patch with the same condition as [PATCH 3/5].

Martin


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