Index: head/sys/kern/subr_blist.c =================================================================== --- head/sys/kern/subr_blist.c +++ head/sys/kern/subr_blist.c @@ -121,8 +121,8 @@ */ static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count); -static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t blk, - daddr_t count, daddr_t radix, int skip); +static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t blk, daddr_t count, + daddr_t radix, daddr_t skip, daddr_t cursor); static void blst_leaf_free(blmeta_t *scan, daddr_t relblk, int count); static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count, daddr_t radix, int skip, daddr_t blk); @@ -177,6 +177,7 @@ bl->bl_blocks = blocks; bl->bl_radix = radix; bl->bl_skip = skip; + bl->bl_cursor = 0; nodes = 1 + blst_radix_init(NULL, radix, bl->bl_skip, blocks); bl->bl_root = malloc(nodes * sizeof(blmeta_t), M_SWAP, flags); if (bl->bl_root == NULL) { @@ -218,13 +219,23 @@ { daddr_t blk; - if (bl != NULL && count <= bl->bl_root->bm_bighint) { + /* + * This loop iterates at most twice. An allocation failure in the + * first iteration leads to a second iteration only if the cursor was + * non-zero. When the cursor is zero, an allocation failure will + * reduce the hint, stopping further iterations. + */ + while (count <= bl->bl_root->bm_bighint) { if (bl->bl_radix == BLIST_BMAP_RADIX) blk = blst_leaf_alloc(bl->bl_root, 0, count); else blk = blst_meta_alloc(bl->bl_root, 0, count, - bl->bl_radix, bl->bl_skip); - return (blk); + bl->bl_radix, bl->bl_skip, bl->bl_cursor); + if (blk != SWAPBLK_NONE) { + bl->bl_cursor = blk + count; + return (blk); + } else if (bl->bl_cursor != 0) + bl->bl_cursor = 0; } return (SWAPBLK_NONE); } @@ -424,16 +435,12 @@ */ static daddr_t -blst_meta_alloc( - blmeta_t *scan, - daddr_t blk, - daddr_t count, - daddr_t radix, - int skip -) { - daddr_t r; - int i; - int next_skip = ((u_int)skip / BLIST_META_RADIX); +blst_meta_alloc(blmeta_t *scan, daddr_t blk, daddr_t count, daddr_t radix, + daddr_t skip, daddr_t cursor) +{ + daddr_t i, next_skip, r; + int child; + bool scan_from_start; if (scan->u.bmu_avail < count) { /* @@ -444,6 +451,7 @@ scan->bm_bighint = scan->u.bmu_avail; return (SWAPBLK_NONE); } + next_skip = skip / BLIST_META_RADIX; /* * An ALL-FREE meta node requires special handling before allocating @@ -457,13 +465,11 @@ * meta node cannot have a terminator in any subtree. */ for (i = 1; i <= skip; i += next_skip) { - if (next_skip == 1) { + if (next_skip == 1) scan[i].u.bmu_bitmap = (u_daddr_t)-1; - scan[i].bm_bighint = BLIST_BMAP_RADIX; - } else { - scan[i].bm_bighint = radix; + else scan[i].u.bmu_avail = radix; - } + scan[i].bm_bighint = radix; } } else { radix /= BLIST_META_RADIX; @@ -476,7 +482,10 @@ */ panic("allocation too large"); } - for (i = 1; i <= skip; i += next_skip) { + scan_from_start = cursor == blk; + child = (cursor - blk) / radix; + blk += child * radix; + for (i = 1 + child * next_skip; i <= skip; i += next_skip) { if (count <= scan[i].bm_bighint) { /* * The allocation might fit in the i'th subtree. @@ -485,7 +494,8 @@ r = blst_leaf_alloc(&scan[i], blk, count); } else { r = blst_meta_alloc(&scan[i], blk, count, - radix, next_skip - 1); + radix, next_skip - 1, cursor > blk ? + cursor : blk); } if (r != SWAPBLK_NONE) { scan->u.bmu_avail -= count; @@ -503,9 +513,10 @@ /* * We couldn't allocate count in this subtree, update bighint. */ - if (scan->bm_bighint >= count) + if (scan_from_start && scan->bm_bighint >= count) scan->bm_bighint = count - 1; - return(SWAPBLK_NONE); + + return (SWAPBLK_NONE); } /* Index: head/sys/sys/blist.h =================================================================== --- head/sys/sys/blist.h +++ head/sys/sys/blist.h @@ -82,6 +82,7 @@ daddr_t bl_blocks; /* area of coverage */ daddr_t bl_radix; /* coverage radix */ daddr_t bl_skip; /* starting skip */ + daddr_t bl_cursor; /* next-fit search starts at */ blmeta_t *bl_root; /* root of radix tree */ } *blist_t;