Improve the svm fifo allocator

- Round up requested fifo size to the next power of two
- Maintain per-segment power-of-two freelists
- Allocate fifos in chunks, to amortize alignment overhead
- Detach builtin test client application after each run
  so we can use different fifo sizes each time
- Be more suspicious of session / application indices

Useful prep work for dynamically resizing fifos. As far as the svm
fifo code is concerned, it's OK to set fifo->nitems anywhere in the
interval: [0, 1<<(fifo->freelist_index) + FIFO_SEGMENT_MIN_FIFO_SIZE]

It's unlikely that setting nitems below the path MTU will work out
very well...

Change-Id: Idad73a027dfb7412056cb02988b77e300fa7e8a7
Signed-off-by: Dave Barach <dave@barachs.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/svm/svm_fifo_segment.h b/src/svm/svm_fifo_segment.h
index a7a3f469bab..68bb4d3d57d 100644
--- a/src/svm/svm_fifo_segment.h
+++ b/src/svm/svm_fifo_segment.h
@@ -27,11 +27,15 @@ typedef enum
   FIFO_SEGMENT_N_FREELISTS
 } svm_fifo_segment_freelist_t;
 
+#define FIFO_SEGMENT_MIN_FIFO_SIZE 2048
+#define FIFO_SEGMENT_MAX_FIFO_SIZE (8<<20)	/* 8mb max fifo size */
+#define FIFO_SEGMENT_ALLOC_CHUNK_SIZE 32	/* allocation quantum */
+
 typedef struct
 {
   svm_fifo_t *fifos;		/**< Linked list of active RX fifos */
   u8 *segment_name;		/**< Segment name */
-  svm_fifo_t *free_fifos[FIFO_SEGMENT_N_FREELISTS];	/**< Free lists */
+  svm_fifo_t **free_fifos;	/**< Freelists, by fifo size  */
 } svm_fifo_segment_header_t;
 
 typedef struct