From 1a744614b682a7a9aec32bbe6ec6ea36a5308166 Mon Sep 17 00:00:00 2001
From: Rom Walton <rwalton@ssl.berkeley.edu>
Date: Sat, 5 Apr 2014 14:28:33 -0400
Subject: [PATCH] VBOX: Introduce a random checkpoint offset value on initial
 start up to interleave the disk I/O when multiple vboxwrappers are running.

---
 samples/vboxwrapper/vboxwrapper.cpp | 39 ++++++++++++++++++++++-------
 win_build/vboxwrapper.vcxproj       |  8 +++---
 2 files changed, 34 insertions(+), 13 deletions(-)

diff --git a/samples/vboxwrapper/vboxwrapper.cpp b/samples/vboxwrapper/vboxwrapper.cpp
index a32aee2b1b..f13636251b 100644
--- a/samples/vboxwrapper/vboxwrapper.cpp
+++ b/samples/vboxwrapper/vboxwrapper.cpp
@@ -372,6 +372,7 @@ int main(int argc, char** argv) {
     BOINC_OPTIONS boinc_options;
     VBOX_VM vm;
     APP_INIT_DATA aid;
+    double random_checkpoint_factor = 0;
     double elapsed_time = 0;
     double trickle_period = 0;
     double fraction_done = 0;
@@ -432,6 +433,29 @@ int main(int argc, char** argv) {
 
     // Log important information
     //
+
+    // Choose a random interleave value for checkpoint intervals to stagger disk I/O.
+    // 
+    random_checkpoint_factor = (double)(((int)(drand() * 100000.0)) % 600);
+    fprintf(
+        stderr,
+        "%s Feature: Checkpoint interval offset (%f seconds)\n",
+        vboxwrapper_msg_prefix(buf, sizeof(buf)),
+        random_checkpoint_factor
+    );
+
+    // Display trickle value if specified
+    //
+    if (trickle_period > 0.0) {
+        fprintf(
+            stderr,
+            "%s Feature: Enabling trickle-ups (Interval: %f)\n",
+            vboxwrapper_msg_prefix(buf, sizeof(buf)), trickle_period
+        );
+    }
+
+    // Initialize system services
+    // 
 #if defined(_WIN32) && defined(USE_WINSOCK)
     WSADATA wsdata;
     retval = WSAStartup( MAKEWORD( 1, 1 ), &wsdata);
@@ -446,14 +470,6 @@ int main(int argc, char** argv) {
     }
 #endif
 
-    if (trickle_period > 0.0) {
-        fprintf(
-            stderr,
-            "%s Feature: Enabling trickle-ups (Interval: %f)\n",
-            vboxwrapper_msg_prefix(buf, sizeof(buf)), trickle_period
-        );
-    }
-
     // Check for architecture incompatibilities
     // 
 #if defined(_WIN32) && defined(_M_IX86)
@@ -973,7 +989,12 @@ int main(int argc, char** argv) {
             if (boinc_time_to_checkpoint()) {
                 // Only peform a VM checkpoint every ten minutes or so.
                 //
-                if (elapsed_time >= checkpoint_cpu_time + 600.0) {
+                if (elapsed_time >= checkpoint_cpu_time + random_checkpoint_factor + 600.0) {
+                    // Basic interleave factor is only needed once.
+                    if (random_checkpoint_factor > 0) {
+                        random_checkpoint_factor = 0.0;
+                    }
+
                     // Basic bookkeeping
                     if (vm.job_duration) {
                         fraction_done = elapsed_time / vm.job_duration;
diff --git a/win_build/vboxwrapper.vcxproj b/win_build/vboxwrapper.vcxproj
index 54405f175e..c21c7b68c6 100644
--- a/win_build/vboxwrapper.vcxproj
+++ b/win_build/vboxwrapper.vcxproj
@@ -128,12 +128,12 @@
     </ResourceCompile>
     <Link>
       <AdditionalDependencies>libcmt.lib;libcpmt.lib;kernel32.lib;user32.lib;gdi32.lib;ole32.lib;wsock32.lib;psapi.lib;%(AdditionalDependencies)</AdditionalDependencies>
-      <OutputFile>.\Build\$(Platform)\$(Configuration)\vboxwrapper_26073_windows_intelx86.exe</OutputFile>
+      <OutputFile>.\Build\$(Platform)\$(Configuration)\vboxwrapper_26077_windows_intelx86.exe</OutputFile>
       <SuppressStartupBanner>true</SuppressStartupBanner>
       <IgnoreAllDefaultLibraries>true</IgnoreAllDefaultLibraries>
       <DelayLoadDLLs>%(DelayLoadDLLs)</DelayLoadDLLs>
       <GenerateDebugInformation>true</GenerateDebugInformation>
-      <ProgramDatabaseFile>.\Build\$(Platform)\$(Configuration)\vboxwrapper_26073_windows_intelx86.pdb</ProgramDatabaseFile>
+      <ProgramDatabaseFile>.\Build\$(Platform)\$(Configuration)\vboxwrapper_26077_windows_intelx86.pdb</ProgramDatabaseFile>
       <SubSystem>Windows</SubSystem>
       <TargetMachine>MachineX86</TargetMachine>
     </Link>
@@ -177,12 +177,12 @@
     </ResourceCompile>
     <Link>
       <AdditionalDependencies>libcmt.lib;libcpmt.lib;kernel32.lib;user32.lib;gdi32.lib;ole32.lib;wsock32.lib;psapi.lib;%(AdditionalDependencies)</AdditionalDependencies>
-      <OutputFile>.\Build\$(Platform)\$(Configuration)\vboxwrapper_26073_windows_x86_64.exe</OutputFile>
+      <OutputFile>.\Build\$(Platform)\$(Configuration)\vboxwrapper_26077_windows_x86_64.exe</OutputFile>
       <SuppressStartupBanner>true</SuppressStartupBanner>
       <IgnoreAllDefaultLibraries>true</IgnoreAllDefaultLibraries>
       <DelayLoadDLLs>%(DelayLoadDLLs)</DelayLoadDLLs>
       <GenerateDebugInformation>true</GenerateDebugInformation>
-      <ProgramDatabaseFile>.\Build\$(Platform)\$(Configuration)\vboxwrapper_26073_windows_x86_64.pdb</ProgramDatabaseFile>
+      <ProgramDatabaseFile>.\Build\$(Platform)\$(Configuration)\vboxwrapper_26077_windows_x86_64.pdb</ProgramDatabaseFile>
       <SubSystem>Windows</SubSystem>
       <TargetMachine>MachineX64</TargetMachine>
     </Link>