Re: [Xen-devel] [PATCH RFC 1/4] tmem: Move global stats in a tmem_statistics structure

[Doug Goldstein <cardoe@xxxxxxxxxx>]

On 5/16/16 10:58 AM, Konrad Rzeszutek Wilk wrote:
> And adjust the macro: atomic_inc_and_max to update the structure.
> 
> Sadly one entry: pool->pgp_count cannot use this macro anymore
> so unroll the macro for this instance.
> 
> No functional change. The name has the 'tmem_stats' as it will
> be eventually non-local.
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  xen/common/tmem.c | 135 
> +++++++++++++++++++++++++++++-------------------------
>  1 file changed, 73 insertions(+), 62 deletions(-)
> 
> diff --git a/xen/common/tmem.c b/xen/common/tmem.c
> index 16e249a..d362eae 100644
> --- a/xen/common/tmem.c
> +++ b/xen/common/tmem.c
> @@ -28,25 +28,32 @@
>  #define TMEM_SPEC_VERSION 1
>  
>  /* Global statistics (none need to be locked). */
> -static unsigned long total_tmem_ops = 0;
> -static unsigned long errored_tmem_ops = 0;
> -static unsigned long total_flush_pool = 0;
> -static unsigned long alloc_failed = 0, alloc_page_failed = 0;
> -static unsigned long evicted_pgs = 0, evict_attempts = 0;
> -static unsigned long relinq_pgs = 0, relinq_attempts = 0;
> -static unsigned long max_evicts_per_relinq = 0;
> -static unsigned long low_on_memory = 0;
> -static unsigned long deduped_puts = 0;
> -static unsigned long tot_good_eph_puts = 0;
> -static int global_obj_count_max = 0;
> -static int global_pgp_count_max = 0;
> -static int global_pcd_count_max = 0;
> -static int global_page_count_max = 0;
> -static int global_rtree_node_count_max = 0;
> -static long global_eph_count_max = 0;
> -static unsigned long failed_copies;
> -static unsigned long pcd_tot_tze_size = 0;
> -static unsigned long pcd_tot_csize = 0;
> +struct tmem_statistics {
> +    unsigned long total_tmem_ops;
> +    unsigned long errored_tmem_ops;
> +    unsigned long total_flush_pool;
> +    unsigned long alloc_failed;
> +    unsigned long alloc_page_failed;
> +    unsigned long evicted_pgs;
> +    unsigned long evict_attempts;
> +    unsigned long relinq_pgs;
> +    unsigned long relinq_attempts;
> +    unsigned long max_evicts_per_relinq;
> +    unsigned long low_on_memory;
> +    unsigned long deduped_puts;
> +    unsigned long tot_good_eph_puts;
> +    int global_obj_count_max;
> +    int global_pgp_count_max;
> +    int global_pcd_count_max;
> +    int global_page_count_max;
> +    int global_rtree_node_count_max;
> +    long global_eph_count_max;
> +    unsigned long failed_copies;
> +    unsigned long pcd_tot_tze_size;
> +    unsigned long pcd_tot_csize;
> +};
> +
> +static struct tmem_statistics tmem_stats;
>  
>  /************ CORE DATA STRUCTURES ************************************/
>  
> @@ -225,8 +232,8 @@ static atomic_t global_rtree_node_count = ATOMIC_INIT(0);
>  
>  #define atomic_inc_and_max(_c) do { \
>      atomic_inc(&_c); \
> -    if ( _atomic_read(_c) > _c##_max ) \
> -        _c##_max = _atomic_read(_c); \
> +    if ( _atomic_read(_c) > tmem_stats._c##_max ) \
> +        tmem_stats._c##_max = _atomic_read(_c); \
>  } while (0)
>  
>  #define atomic_dec_and_assert(_c) do { \
> @@ -273,7 +280,7 @@ static void *tmem_malloc(size_t size, struct tmem_pool 
> *pool)
>          v = xmem_pool_alloc(size, tmem_mempool);
>      }
>      if ( v == NULL )
> -        alloc_failed++;
> +        tmem_stats.alloc_failed++;
>      return v;
>  }
>  
> @@ -300,7 +307,7 @@ static struct page_info *tmem_alloc_page(struct tmem_pool 
> *pool)
>      else
>          pfp = __tmem_alloc_page();
>      if ( pfp == NULL )
> -        alloc_page_failed++;
> +        tmem_stats.alloc_page_failed++;
>      else
>          atomic_inc_and_max(global_page_count);

So the code was previously like this but this change made me notice
this. How come tmem_stats.global_page_count needs to be atomically
incremented but not tmem_stats.alloc_page_failed? Its also a little
weird that global_page_count is in the struct now but not really visible
here while alloc_page_count is in the struct but has to be explicitly
called out.


-- 
Doug Goldstein

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