Meta Alloc size classes start at 256.

3 files changed, 9 insertions, 9 deletions

diff --git a/MetaAlloc.ods b/MetaAlloc.ods
index a3d88ea..1313aab 100644
--- a/MetaAlloc.ods
+++ b/MetaAlloc.ods
diff --git a/doc/0/A-meta_alloc.md b/doc/0/A-meta_alloc.md
index 85c704c..7383ec2 100644
--- a/doc/0/A-meta_alloc.md
+++ b/doc/0/A-meta_alloc.md
@@ -104,14 +104,14 @@ Zisp runtime, that the operating system reports that the process is
 using hundreds of gigabytes of virtual memory, do not panic; it's a
 feature, not a bug, and completely benign.
 
-As for the size classes: They simply go from 128 bytes to 4 MiB in
-perfect powers of two; in other words, from 2^7 to 2^22.  There are
-certain benefits to using exact powers of two, and 128 bytes - 4 MiB
+As for the size classes: They simply go from 256 bytes to 8 MiB in
+perfect powers of two; in other words, from 2^8 to 2^23.  There are
+certain benefits to using exact powers of two, and 256 bytes - 8 MiB
 seems like a reasonable range.  Code using Meta Alloc must be aware
 that only these size classes are supported, and try to make optimal
 use of them.
 
-**WARNING:** Calling `alloc()` with a size smaller than 128 or one
+**WARNING:** Calling `alloc()` with a size smaller than 256 or one
 that is not a perfect power of two will lead to catastrophic bugs
 under optimized builds of Zisp.
 
@@ -218,11 +218,11 @@ values used by the implementation are as follows:
 
 * Maximum count: 16 Indexes
 
-* Smallest size class: 128 bytes
+* Smallest size class: 256 bytes
 
 The extra Index array starts after 64 bytes, and requires 64 bytes,
-since it stores up to 16 32-bit integers; that's a total size of 128,
-which fits exactly into the smallest size.
+since it stores up to 16 32-bit integers; that's a total size of 256,
+which fits into the smallest size.
 
 The 64-byte padding is to allow for efficient bulk memory transfer
 using up to 512-bit SIMD instructions on modern processors.
diff --git a/src/zisp/gc/meta_alloc.zig b/src/zisp/gc/meta_alloc.zig
index c8d46e1..248b00b 100644
--- a/src/zisp/gc/meta_alloc.zig
+++ b/src/zisp/gc/meta_alloc.zig
@@ -107,7 +107,6 @@ const SIZES: [16]usize = .{
     // Important: Ensure the smallest size class is inherently immune to false
     // sharing, and no smaller than: 64 + @sizeOf(UnitIdx) * ( FSC_MAX / 2 ).
     // That's exactly 128 bytes assuming FSC_MAX = 32 (see below).
-    128,
     256,
     512,
     1024,
@@ -123,6 +122,7 @@ const SIZES: [16]usize = .{
     1024 * 1024,
     1024 * 1024 * 2,
     1024 * 1024 * 4,
+    1024 * 1024 * 8,
 };
 
 /// Gets the index 0 to 15 of a size class, from the size value, returning a
@@ -520,7 +520,7 @@ export fn flush_thread_reserves() void {
 
         // Given our chunked WM bumps and smallest size class, hi - lo > 4 KiB
         // implies that there's at least one entire untouched page, as well as
-        // at least one >=128-byte slot before it, which can hold the metadata
+        // at least one >=256-byte slot before it, which can hold the metadata
         // of the vacancy-list entry without faulting in an empty page.
         if (tl.wm_hi - tl.wm_lo > 4096 / @sizeOf(Unit)) {
             flush_to_vl(info, tl, slab);