From 9debca9f193f31c2c791f1b752e588b512adae73 Mon Sep 17 00:00:00 2001
From: David Carlier <devnexen@gmail.com>
Date: Tue, 17 Dec 2024 23:14:06 +0000
Subject: [PATCH] sys::man adding `MADV_POPULATE_READ` and
 `MAP_POPULATE_WRITE`.

More specialised than MmapFlags::MAP_POPULATE, another difference being
it does not silently fail.

- `MADV_POPULATE_READ` to pre-populate pages ahead of read accesses.
- `MADV_POPULATE_WRITE` to pre-populate pages ahead of subsequent
  writes.
---
 src/sys/mman.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/sys/mman.rs b/src/sys/mman.rs
index 833e8e182d..6bd724379a 100644
--- a/src/sys/mman.rs
+++ b/src/sys/mman.rs
@@ -328,6 +328,13 @@ libc_enum! {
         /// Undo `MADV_WIPEONFORK` when it applied.
         #[cfg(linux_android)]
         MADV_KEEPONFORK,
+        /// Pre-load the address range for reading to reduce page-fault latency.
+        #[cfg(linux_android)]
+        MADV_POPULATE_READ,
+        /// Pre-fault the address range for writing to reduce page-fault
+        /// latency on subsequent writes.
+        #[cfg(linux_android)]
+        MADV_POPULATE_WRITE,
     }
 }