From fec27a2db22d2aaabd867f1822a16e810c0dc5c4 Mon Sep 17 00:00:00 2001
From: qijun <qijun1994@hotmail.com>
Date: Thu, 7 Dec 2017 14:53:46 +0800
Subject: [PATCH 1/4] fix gpu memory allocation policy

---
 paddle/memory/detail/system_allocator.cc |  2 +-
 paddle/memory/memory.cc                  | 18 +++++++++++-------
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/paddle/memory/detail/system_allocator.cc b/paddle/memory/detail/system_allocator.cc
index 6b4e46f56a0c9c..b543b767e8015f 100644
--- a/paddle/memory/detail/system_allocator.cc
+++ b/paddle/memory/detail/system_allocator.cc
@@ -83,7 +83,7 @@ void* GPUAllocator::Alloc(size_t& index, size_t size) {
   paddle::platform::GpuMemoryUsage(available, capacity);
 
   // Reserve memory for page tables, etc.
-  size_t reserving = capacity - paddle::platform::GpuMaxAllocSize();
+  size_t reserving = 0.05 * capacity + paddle::platform::GpuMinChunkSize();
   size_t usable = available > reserving ? available - reserving : 0;
 
   // If remaining size no less than expected size, using general
diff --git a/paddle/memory/memory.cc b/paddle/memory/memory.cc
index 95cfe2525e3e7c..6b50d1908eac63 100644
--- a/paddle/memory/memory.cc
+++ b/paddle/memory/memory.cc
@@ -64,19 +64,23 @@ BuddyAllocator* GetGPUBuddyAllocator(int gpu_id) {
     int gpu_num = platform::GetCUDADeviceCount();
     as = new BuddyAllocator*[gpu_num];
     for (int gpu = 0; gpu < gpu_num; gpu++) {
-      platform::SetDeviceId(gpu);
-      as[gpu] = new BuddyAllocator(new detail::GPUAllocator,
-                                   platform::GpuMinChunkSize(),
-                                   platform::GpuMaxChunkSize());
+      as[gpu] = nullptr;
     }
+  }
+  platform::SetDeviceId(gpu_id);
+  if (as[gpu_id]) {
+    return as[gpu_id];
+  } else {
+    as[gpu_id] = new BuddyAllocator(new detail::GPUAllocator,
+                                 platform::GpuMinChunkSize(),
+                                 platform::GpuMaxChunkSize());
     VLOG(10) << "\n\nNOTE: each GPU device use "
              << FLAGS_fraction_of_gpu_memory_to_use * 100
              << "% of GPU memory.\n"
-             << "You can set environment variable '"
-             << platform::kEnvFractionGpuMemoryToUse
+             << "You can set GFlags environment variable '"
+             << "FLAGS_fraction_of_gpu_memory_to_use"
              << "' to change the fraction of GPU usage.\n\n";
   }
-  platform::SetDeviceId(gpu_id);
   return as[gpu_id];
 }
 

From 0f24177e260b6c041361ac9beda2cfa9efc61a30 Mon Sep 17 00:00:00 2001
From: qijun <qijun1994@hotmail.com>
Date: Thu, 7 Dec 2017 15:05:14 +0800
Subject: [PATCH 2/4] refine codes

---
 paddle/memory/memory.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/paddle/memory/memory.cc b/paddle/memory/memory.cc
index 6b50d1908eac63..fa68c9f349694c 100644
--- a/paddle/memory/memory.cc
+++ b/paddle/memory/memory.cc
@@ -80,8 +80,8 @@ BuddyAllocator* GetGPUBuddyAllocator(int gpu_id) {
              << "You can set GFlags environment variable '"
              << "FLAGS_fraction_of_gpu_memory_to_use"
              << "' to change the fraction of GPU usage.\n\n";
+    return as[gpu_id];
   }
-  return as[gpu_id];
 }
 
 template <>

From f914b33bbff849b91036cf13492d0adfe7fda7cd Mon Sep 17 00:00:00 2001
From: qijun <qijun1994@hotmail.com>
Date: Thu, 7 Dec 2017 16:24:53 +0800
Subject: [PATCH 3/4] fix code style

---
 paddle/memory/memory.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/paddle/memory/memory.cc b/paddle/memory/memory.cc
index fa68c9f349694c..13553cc6a9b95f 100644
--- a/paddle/memory/memory.cc
+++ b/paddle/memory/memory.cc
@@ -72,8 +72,8 @@ BuddyAllocator* GetGPUBuddyAllocator(int gpu_id) {
     return as[gpu_id];
   } else {
     as[gpu_id] = new BuddyAllocator(new detail::GPUAllocator,
-                                 platform::GpuMinChunkSize(),
-                                 platform::GpuMaxChunkSize());
+                                    platform::GpuMinChunkSize(),
+                                    platform::GpuMaxChunkSize());
     VLOG(10) << "\n\nNOTE: each GPU device use "
              << FLAGS_fraction_of_gpu_memory_to_use * 100
              << "% of GPU memory.\n"

From a106329c770dc0c9482c40300641dab58f293de0 Mon Sep 17 00:00:00 2001
From: qijun <qijun1994@hotmail.com>
Date: Thu, 7 Dec 2017 18:27:17 +0800
Subject: [PATCH 4/4] follow comments

---
 paddle/memory/memory.cc | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/paddle/memory/memory.cc b/paddle/memory/memory.cc
index 13553cc6a9b95f..9cafdfda75d051 100644
--- a/paddle/memory/memory.cc
+++ b/paddle/memory/memory.cc
@@ -68,9 +68,7 @@ BuddyAllocator* GetGPUBuddyAllocator(int gpu_id) {
     }
   }
   platform::SetDeviceId(gpu_id);
-  if (as[gpu_id]) {
-    return as[gpu_id];
-  } else {
+  if (!as[gpu_id]) {
     as[gpu_id] = new BuddyAllocator(new detail::GPUAllocator,
                                     platform::GpuMinChunkSize(),
                                     platform::GpuMaxChunkSize());
@@ -80,8 +78,8 @@ BuddyAllocator* GetGPUBuddyAllocator(int gpu_id) {
              << "You can set GFlags environment variable '"
              << "FLAGS_fraction_of_gpu_memory_to_use"
              << "' to change the fraction of GPU usage.\n\n";
-    return as[gpu_id];
   }
+  return as[gpu_id];
 }
 
 template <>