svm: allow indirect fifo data chunks

Fifos can use multiple memory chunks for simple read/write operations.
Adding/removing chunks after assignment not yet supported.

Change-Id: I2aceab6aea78059d74e0d3a9993c40d5196d077b
Signed-off-by: Florin Coras <fcoras@cisco.com>

1 files changed, 19 insertions, 6 deletions

diff --git a/src/svm/svm_fifo.h b/src/svm/svm_fifo.h
index 94a05938d26..f311576f5af 100644
--- a/src/svm/svm_fifo.h
+++ b/src/svm/svm_fifo.h
@@ -60,11 +60,21 @@ typedef struct
   u32 action;
 } svm_fifo_trace_elem_t;
 
+typedef struct svm_fifo_chunk_
+{
+  u32 start_byte;
+  u32 length;
+  struct svm_fifo_chunk_ *next;
+  u8 data[0];
+} svm_fifo_chunk_t;
+
 typedef struct _svm_fifo
 {
   CLIB_CACHE_LINE_ALIGN_MARK (shared_first);
-  u32 size;			/**< size of the fifo(must be power of 2) */
+  u32 size;			/**< size of the fifo */
   u32 nitems;			/**< usable size(size-1) */
+  struct _svm_fifo *next;	/**< next in freelist/active chain */
+  struct _svm_fifo *prev;	/**< prev in active chain */
 
     CLIB_CACHE_LINE_ALIGN_MARK (shared_second);
   volatile u32 has_event;	/**< non-zero if deq event exists */
@@ -81,17 +91,17 @@ typedef struct _svm_fifo
 
     CLIB_CACHE_LINE_ALIGN_MARK (consumer);
   u32 head;
+  svm_fifo_chunk_t *head_chunk;
   volatile u32 want_tx_ntf;	/**< producer wants nudge */
   volatile u32 has_tx_ntf;
 
     CLIB_CACHE_LINE_ALIGN_MARK (producer);
   u32 tail;
+  svm_fifo_chunk_t *tail_chunk;
 
   ooo_segment_t *ooo_segments;	/**< Pool of ooo segments */
   u32 ooos_list_head;		/**< Head of out-of-order linked-list */
   u32 ooos_newest;		/**< Last segment to have been updated */
-  struct _svm_fifo *next;	/**< next in freelist/active chain */
-  struct _svm_fifo *prev;	/**< prev in active chain */
   volatile u8 n_subscribers;
   u8 subscribers[SVM_FIFO_MAX_EVT_SUBSCRIBERS];
 
@@ -99,7 +109,7 @@ typedef struct _svm_fifo
   svm_fifo_trace_elem_t *trace;
 #endif
 
-    CLIB_CACHE_LINE_ALIGN_MARK (data);
+  svm_fifo_chunk_t default_chunk;
 } svm_fifo_t;
 
 typedef enum
@@ -305,6 +315,7 @@ svm_fifo_unset_event (svm_fifo_t * f)
 }
 
 svm_fifo_t *svm_fifo_create (u32 data_size_in_bytes);
+void svm_fifo_init (svm_fifo_t * f, u32 size);
 void svm_fifo_free (svm_fifo_t * f);
 
 int svm_fifo_enqueue_nowait (svm_fifo_t * f, u32 max_bytes,
@@ -373,14 +384,16 @@ always_inline u8 *
 svm_fifo_head (svm_fifo_t * f)
 {
   /* load-relaxed: consumer owned index */
-  return (f->data + (f->head % f->size));
+  return (f->head_chunk->data
+	  + ((f->head % f->size) - f->head_chunk->start_byte));
 }
 
 always_inline u8 *
 svm_fifo_tail (svm_fifo_t * f)
 {
   /* load-relaxed: producer owned index */
-  return (f->data + (f->tail % f->size));
+  return (f->tail_chunk->data
+	  + ((f->tail % f->size) - f->tail_chunk->start_byte));
 }
 
 static inline void