From efe2822708d62bfe3ba858da526e6ef7d4724959 Mon Sep 17 00:00:00 2001
From: Jean Boussier <byroot@ruby-lang.org>
Date: Fri, 15 Sep 2023 16:22:09 +0200
Subject: [PATCH] Process.warmup: invoke `malloc_trim` if available

Similar to releasing free GC pages, releasing free malloc pages
reduce the amount of page faults post fork.
---
 configure.ac | 1 +
 gc.c         | 4 ++++
 process.c    | 1 +
 3 files changed, 6 insertions(+)

diff --git a/configure.ac b/configure.ac
index 30a1350fa6..70400dd797 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2078,6 +2078,7 @@ AC_CHECK_FUNCS(lstat)
 AC_CHECK_FUNCS(lutimes)
 AC_CHECK_FUNCS(malloc_usable_size)
 AC_CHECK_FUNCS(malloc_size)
+AC_CHECK_FUNCS(malloc_trim)
 AC_CHECK_FUNCS(mblen)
 AC_CHECK_FUNCS(memalign)
 AC_CHECK_FUNCS(memset_s)
diff --git a/gc.c b/gc.c
index 3fd2a3b33f..662ddc3e0f 100644
--- a/gc.c
+++ b/gc.c
@@ -9740,6 +9740,10 @@ rb_gc_prepare_heap(void)
     rb_objspace_each_objects(gc_set_candidate_object_i, NULL);
     gc_start_internal(NULL, Qtrue, Qtrue, Qtrue, Qtrue, Qtrue);
     free_empty_pages();
+
+#if defined(HAVE_MALLOC_TRIM) && !defined(RUBY_ALTERNATIVE_MALLOC_HEADER)
+    malloc_trim(0);
+#endif
 }
 
 static int
diff --git a/process.c b/process.c
index d7e04830ee..690872ad36 100644
--- a/process.c
+++ b/process.c
@@ -8789,6 +8789,7 @@ static VALUE rb_mProcID_Syscall;
  *  * Precomputes the coderange of all strings.
  *  * Frees all empty heap pages and increments the allocatable pages counter
  *    by the number of pages freed.
+ *  * Invoke +malloc_trim+ if available to free empty malloc pages.
  */
 
 static VALUE