hash: use kernel readahead instead of bees_readahead to prefetch hash table

The hash table is read sequentially and from a single thread, so
the kernel's implementation of readahead is appropriate here.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

diff --git a/src/bees-hash.cc b/src/bees-hash.cc
index 4877b7d441012623ba8b0a5f1e65e5e661b9b7b9..0ec092abe0653b134b031430eb40b799dad17ed1 100644 (file)
--- a/src/bees-hash.cc
+++ b/src/bees-hash.cc
@@ -446,8 +446,8 @@ BeesHashTable::fetch_missing_extent_by_index(uint64_t extent_index)
 
                // If we are in prefetch, give the kernel a hint about the next extent
                if (m_prefetch_running) {
-                       // XXX: don't call this if bees_readahead is implemented by pread()
-                       bees_readahead(m_fd, dirty_extent_offset + dirty_extent_size, dirty_extent_size);
+                       // Use the kernel readahead here, because it might work for this use case
+                       readahead(m_fd, dirty_extent_offset + dirty_extent_size, dirty_extent_size);
                }
        });
 }