Add prefetch

timescale_vector/Cargo.toml

@@ -26,6 +26,7 @@ rand_chacha = "0.3"
 rand_core = "0.6"
 rand_xorshift = "0.3"
 rayon = "1"
+libc = "0.2.150"
 
 
 [dev-dependencies]

timescale_vector/src/access_method/graph.rs

@@ -528,6 +528,10 @@ pub trait Graph {
                 panic!("Nodes in the list search results that aren't in the builder");
             }
 
+            for neighbor_index_pointer in &neighbors {
+                unsafe { (*neighbor_index_pointer).prefetch(index) };
+            }
+
             for neighbor_index_pointer in &neighbors {
                 lsr.insert(index, self, *neighbor_index_pointer, query)
             }

timescale_vector/src/util/mod.rs

@@ -3,9 +3,15 @@ pub mod page;
 pub mod ports;
 pub mod tape;
 
-use pgrx::PgRelation;
+use pgrx::{
+    error,
+    pg_sys::{BufferGetPage, ForkNumber_MAIN_FORKNUM, BLCKSZ},
+    PgRelation,
+};
 use rkyv::{Archive, Deserialize, Serialize};
 
+use std::io::Error;
+
 use self::{
     page::{ReadablePage, WritablePage},
     ports::{PageGetItem, PageGetItemId},
@@ -81,6 +87,22 @@ impl ItemPointer {
         pgrx::item_pointer_set_all(ctid, self.block_number, self.offset)
     }
 
+    pub unsafe fn prefetch(self, index: &PgRelation) {
+        let res = pgrx::pg_sys::PrefetchBuffer(
+            index.as_ptr(),
+            ForkNumber_MAIN_FORKNUM,
+            self.block_number,
+        );
+        if res.recent_buffer > 0 {
+            let ptr = BufferGetPage(res.recent_buffer - 1);
+            let res = libc::madvise(ptr as _, BLCKSZ as usize, libc::MADV_WILLNEED);
+            if res != 0 {
+                let err = Error::last_os_error();
+                error!("Error in madvise: {}", err);
+            }
+        }
+    }
+
     pub unsafe fn read_bytes(self, index: &PgRelation) -> ReadableBuffer {
         let page = ReadablePage::read(index, self.block_number);
         let item_id = PageGetItemId(*page, self.offset);