Bring back cramming to fellow_busy_seg_memalloc()

Ref #60

src/fellow_cache.c

@@ -827,7 +827,7 @@ struct fellow_busy_io_seglist {
 // pool for segment memory
 BUDDY_POOL(fbo_segmem, 1);
 BUDDY_POOL_GET_FUNC(fbo_segmem, static)
-//BUDDY_POOL_AVAIL_FUNC(fbo_segmem, static)
+BUDDY_POOL_AVAIL_FUNC(fbo_segmem, static)
 
 struct fellow_busy_io {
 	uint16_t				magic;
@@ -4941,16 +4941,21 @@ fellow_busy_body_seg_next(struct fellow_busy *fbo)
  *
  * used for body and auxattr
  */
-static size_t fellow_busy_seg_memalloc(struct fellow_busy *fbo,
+static size_t
+fellow_busy_seg_memalloc(struct fellow_busy *fbo,
     struct fellow_cache_seg *fcs, int8_t cram)
 {
 	struct fellow_disk_seg *fds;
 	struct buddy_ptr_page mem;
+	struct fellow_cache *fc;
+	unsigned bits;
 	size_t sz;
 
 	CHECK_OBJ_NOTNULL(fcs, FELLOW_CACHE_SEG_MAGIC);
 	fds = fcs->disk_seg;
 	CHECK_OBJ_NOTNULL(fds, FELLOW_DISK_SEG_MAGIC);
+	fc = fbo->fc;
+	CHECK_OBJ_NOTNULL(fc, FELLOW_CACHE_MAGIC);
 
 	assert (fcs->state == FCS_USABLE);
 	AN(fds->seg.off);
@@ -4962,13 +4967,33 @@ static size_t fellow_busy_seg_memalloc(struct fellow_busy *fbo,
 	if (FC_INJ)
 		return (0);
 
+	bits = log2up(fds->seg.size);
+	assert(bits >= MIN_FELLOW_BITS);
+	assert(bits <= INT8_MAX);
+
 	if (cram != 0) {
-		cram = buddy_cramlimit_extent_minbits(fds->seg.size,
-		    fbo->fc->tune->cram, MIN_FELLOW_BITS);
+		cram = buddy_cramlimit_page_minbits((int8_t)bits,
+		    fc->tune->cram, MIN_FELLOW_BITS);
+	}
+
+	/*
+	 * the fbo_segmem pool does not cram - because it pre-allocates,
+	 * this is the best option. But if it is waiting, use a crammed
+	 * immediate allocation. If that fails, wait on the pool
+	 * to avoid double waiting allocations.
+	 */
+
+	mem = buddy_ptr_page_nil;
+
+	if (! fbo_segmem_avail(fbo->segmem)) {
+		mem = buddy_alloc1_ptr_page(fc->membuddy,
+		    (uint8_t)bits, cram);
+	}
+	if (mem.ptr == NULL) {
+		mem = buddy_get_next_ptr_page(
+		    fbo_segmem_get(fbo->segmem, fc->tune));
 	}
 
-	mem = buddy_get_next_ptr_page(
-	    fbo_segmem_get(fbo->segmem, fbo->fc->tune));
 	AN(mem.ptr);
 	sz = (size_t)1 << mem.bits;
 
@@ -4976,14 +5001,14 @@ static size_t fellow_busy_seg_memalloc(struct fellow_busy *fbo,
 	 * if the fbo_segmem pool gave us too large/small a page,
 	 * trade it in for a new allocation
 	 */
-	if (log2up(fds->seg.size) < mem.bits ||
+	if (bits < mem.bits ||
 	    (cram == 0 && sz < fds->seg.size)) {
 		struct buddy_reqs *reqs =
-		    BUDDY_REQS_STK(fbo->fc->membuddy, 1);
+		    BUDDY_REQS_STK(fc->membuddy, 1);
 
 		BUDDY_REQS_PRI(reqs, FEP_SPCPRI);
 		AN(buddy_req_extent(reqs, fds->seg.size, 0));
-		buddy_return1_ptr_page(fbo->fc->membuddy, &mem);
+		buddy_return1_ptr_page(fc->membuddy, &mem);
 		AN(buddy_alloc_wait(reqs));
 		fcs->alloc = buddy_get_ptr_extent(reqs, 0);
 		buddy_alloc_wait_done(reqs);
@@ -4997,7 +5022,7 @@ static size_t fellow_busy_seg_memalloc(struct fellow_busy *fbo,
 		return (0);
 
 	if (fds->seg.size < fcs->alloc.size) {
-		buddy_trim1_ptr_extent(fbo->fc->membuddy, &fcs->alloc,
+		buddy_trim1_ptr_extent(fc->membuddy, &fcs->alloc,
 		    fds->seg.size);
 	}