From 3b6f3b2d025c9bf2dac4de61ea92ca0df077b171 Mon Sep 17 00:00:00 2001
From: Jared Duke <jdduke@google.com>
Date: Tue, 23 Apr 2024 20:40:37 +0000
Subject: Madvise uncompressed app images

We currently only madvise compressed app images, which accelerates
the immediate software decompression. However, uncompressed app images
also benefit from explicit madvise calls, as they are immediately
patched after mmap. This patching ends up dirtying most pages, and a
preceding madvise avoids excessive faulting during the fixup.

Bug: 336349058
Test: m + ART benchmark service w/ uncompressed app images
Change-Id: Ica9786e2dd01df338bff44d787d1dd0b82c48809
---
 runtime/gc/space/image_space.cc | 49 +++++++++++++++++++++--------------------
 1 file changed, 25 insertions(+), 24 deletions(-)

diff --git a/runtime/gc/space/image_space.cc b/runtime/gc/space/image_space.cc
index 7f1bde2426..852039a206 100644
--- a/runtime/gc/space/image_space.cc
+++ b/runtime/gc/space/image_space.cc
@@ -995,24 +995,34 @@ class ImageSpace::Loader {
                               /*out*/std::string* error_msg)
         REQUIRES_SHARED(Locks::mutator_lock_) {
     TimingLogger::ScopedTiming timing("MapImageFile", logger);
-    std::string temp_error_msg;
+
+    // The runtime might not be available at this point if we're running dex2oat or oatdump, in
+    // which case we just truncate the madvise optimization limit completely.
+    Runtime* runtime = Runtime::Current();
+    const size_t madvise_size_limit = runtime ? runtime->GetMadviseWillNeedSizeArt() : 0;
+
     const bool is_compressed = image_header.HasCompressedBlock();
     if (!is_compressed && allow_direct_mapping) {
       uint8_t* address = (image_reservation != nullptr) ? image_reservation->Begin() : nullptr;
       // The reserved memory size is aligned up to kElfSegmentAlignment to ensure
       // that the next reserved area will be aligned to the value.
-      return MemMap::MapFileAtAddress(address,
-                                      CondRoundUp<kPageSizeAgnostic>(image_header.GetImageSize(),
-                                                                     kElfSegmentAlignment),
-                                      PROT_READ | PROT_WRITE,
-                                      MAP_PRIVATE,
-                                      fd,
-                                      /*start=*/ 0,
-                                      /*low_4gb=*/ true,
-                                      image_filename,
-                                      /*reuse=*/ false,
-                                      image_reservation,
-                                      error_msg);
+      MemMap map = MemMap::MapFileAtAddress(
+          address,
+          CondRoundUp<kPageSizeAgnostic>(image_header.GetImageSize(), kElfSegmentAlignment),
+          PROT_READ | PROT_WRITE,
+          MAP_PRIVATE,
+          fd,
+          /*start=*/0,
+          /*low_4gb=*/true,
+          image_filename,
+          /*reuse=*/false,
+          image_reservation,
+          error_msg);
+      if (map.IsValid()) {
+        Runtime::MadviseFileForRange(
+            madvise_size_limit, map.Size(), map.Begin(), map.End(), image_filename);
+      }
+      return map;
     }
 
     // Reserve output and copy/decompress into it.
@@ -1040,17 +1050,8 @@ class ImageSpace::Loader {
         return MemMap::Invalid();
       }
 
-      Runtime* runtime = Runtime::Current();
-      // The runtime might not be available at this point if we're running
-      // dex2oat or oatdump.
-      if (runtime != nullptr) {
-        size_t madvise_size_limit = runtime->GetMadviseWillNeedSizeArt();
-        Runtime::MadviseFileForRange(madvise_size_limit,
-                                     temp_map.Size(),
-                                     temp_map.Begin(),
-                                     temp_map.End(),
-                                     image_filename);
-      }
+      Runtime::MadviseFileForRange(
+          madvise_size_limit, temp_map.Size(), temp_map.Begin(), temp_map.End(), image_filename);
 
       if (is_compressed) {
         memcpy(map.Begin(), &image_header, sizeof(ImageHeader));
-- 
cgit v1.2.3