The dumbest scalable inode allocator.

Split the inode space into per-cpu spaces of size IPB that start at the begining of a block. Block awareness is important to avoid contention on blocks themselves when allocating or freeing an inode and updating on-disk structures. That is, I don't want to make bio scalable.

The dumbest scalable inode allocator.
2c2b6c84 · Silas Boyd-Wickizer · 54f5af15 · 2c2b6c84
--- a/kernel/fs.cc
+++ b/kernel/fs.cc
@@ -166,6 +166,17 @@ initinode(void)
  if (ins->insert(make_pair(the_root->dev, the_root->inum), the_root) < 0)
    panic("initinode: insert the_root failed");
  the_root->init();
+  if (VERBOSE) {
+    struct superblock sb;
+    u64 blocks;
+    readsb(ROOTDEV, &sb);
+    blocks = sb.ninodes/IPB;
+    cprintf("initinode: %lu inode blocks (%lu / core)\n",
+            blocks, blocks/NCPU);
+  }
 }
 //PAGEBREAK!
@@ -174,13 +185,15 @@ initinode(void)
 struct inode*
 ialloc(u32 dev, short type)
 {
-  int inum;
  struct buf *bp;
  struct dinode *dip;
  struct superblock sb;
  readsb(dev, &sb);
-  for(inum = 1; inum < sb.ninodes; inum++){  // loop over inode blocks
+  for (int k = mycpuid()*IPB; k < sb.ninodes; k += (NCPU*IPB)) {
+    for(int inum = k; inum < k+IPB && inum < sb.ninodes; inum++){
+      if (inum == 0)
+        continue;
      bp = bread(dev, IBLOCK(inum), 0);
      dip = (struct dinode*)bp->data + inum%IPB;
      int seemsfree = (dip->type == 0);
@@ -203,6 +216,7 @@ ialloc(u32 dev, short type)
        //cprintf("ialloc oops %d\n", inum); // XXX harmless
      }
    }
+  }
  cprintf("ialloc: 0/%u inodes\n", sb.ninodes);
  return nullptr;
 }