Introduce a new sysctl, vm.zone_stats, which exports UMA(9) allocator

statistics via a binary structure stream:

- Add structure 'uma_stream_header', which defines a stream version,
  definition of MAXCPUs used in the stream, and the number of zone
  records in the stream.

- Add structure 'uma_type_header', which defines the name, alignment,
  size, resource allocation limits, current pages allocated, preferred
  bucket size, and central zone + keg statistics.

- Add structure 'uma_percpu_stat', which, for each per-CPU cache,
  includes the number of allocations and frees, as well as the number
  of free items in the cache.

- When the sysctl is queried, return a stream header, followed by a
  series of type descriptions, each consisting of a type header
  followed by a series of MAXCPUs uma_percpu_stat structures holding
  per-CPU allocation information.  Typical values of MAXCPU will be
  1 (UP compiled kernel) and 16 (SMP compiled kernel).

This query mechanism allows user space monitoring tools to extract
memory allocation statistics in a machine-readable form, and to do so
at a per-CPU granularity, allowing monitoring of allocation patterns
across CPUs in order to better understand the distribution of work and
memory flow over multiple CPUs.

While here, also export the number of UMA zones as a sysctl
vm.uma_count, in order to assist in sizing user swpace buffers to
receive the stream.

A follow-up commit of libmemstat(3), a library to monitor kernel memory
allocation, will occur in the next few days.  This change directly
supports converting netstat(1)'s "-mb" mode to using UMA-sourced stats
rather than separately maintained mbuf allocator statistics.

MFC after:	1 week

1 files changed, 47 insertions, 0 deletions

diff --git a/sys/vm/uma.h b/sys/vm/uma.h
index 2152b4d..283be9f 100644
--- a/sys/vm/uma.h
+++ b/sys/vm/uma.h
@@ -509,4 +509,51 @@ void uma_prealloc(uma_zone_t zone, int itemcnt);
  */
 u_int32_t *uma_find_refcnt(uma_zone_t zone, void *item);
 
+/*
+ * Exported statistics structures to be used by user space monitoring tools.
+ * Statistics stream consusts of a uma_stream_header, followed by a series of
+ * alternative uma_type_header and uma_type_stat structures.  Statistics
+ * structures
+ */
+#define	UMA_STREAM_VERSION	0x00000001
+struct uma_stream_header {
+	u_int32_t	ush_version;	/* Stream format version. */
+	u_int32_t	ush_maxcpus;	/* Value of MAXCPU for stream. */
+	u_int32_t	ush_count;	/* Number of records. */
+	u_int32_t	_ush_pad;	/* Pad/reserved field. */
+};
+
+#define	UMA_MAX_NAME	32
+struct uma_type_header {
+	/*
+	 * Static per-zone data, some extracted from the supporting keg.
+	 */
+	char		uth_name[UMA_MAX_NAME];
+	u_int32_t	uth_align;	/* Keg: alignment. */
+	u_int32_t	uth_size;	/* Keg: requested size of item. */
+	u_int32_t	uth_rsize;	/* Keg: real size of item. */
+	u_int32_t	uth_maxpages;	/* Keg: maximum number of pages. */
+	u_int32_t	uth_limit;	/* Keg: max items to allocate. */
+
+	/*
+	 * Current dynamic zone/keg-derived statistics.
+	 */
+	u_int32_t	uth_pages;	/* Keg: pages allocated. */
+	u_int32_t	uth_keg_free;	/* Keg: items free. */
+	u_int32_t	uth_zone_free;	/* Zone: items free. */
+	u_int32_t	uth_bucketsize;	/* Zone: desired bucket size. */
+	u_int32_t	_uth_reserved0;	/* Reserved. */
+	u_int64_t	uth_allocs;	/* Zone: number of allocations. */
+	u_int64_t	uth_frees;	/* Zone: number of frees. */
+	u_int64_t	_uth_reserved1[4];	/* Reserved. */
+
+};
+
+struct uma_percpu_stat {
+	u_int64_t	ups_allocs;	/* Cache: number of alloctions. */
+	u_int64_t	ups_frees;	/* Cache: number of frees. */
+	u_int64_t	ups_cache_free;	/* Cache: free items in cache. */
+	u_int64_t	_ups_reserved[5];	/* Reserved. */
+};
+
 #endif