From bbda6e1262f8cf6ff62a240dd80a34a043db1ec5 Mon Sep 17 00:00:00 2001
From: Carl Pearson <pearson@illinois.edu>
Date: Tue, 1 Oct 2019 06:55:50 -0500
Subject: [PATCH] add interface for scheduling priority

---
 README.md                           | 12 ++++++++++++
 examples/CMakeLists.txt             |  3 +++
 examples/high_priority.cpp          | 12 ++++++++++++
 include/perfect/detail/os/linux.hpp | 13 +++++++++++++
 include/perfect/priority.hpp        | 15 +++++++++++++++
 tools/perfect.cpp                   | 11 ++++++++++-
 6 files changed, 65 insertions(+), 1 deletion(-)
 create mode 100644 examples/high_priority.cpp
 create mode 100644 include/perfect/priority.hpp

diff --git a/README.md b/README.md
index 2d060db..d77c922 100644
--- a/README.md
+++ b/README.md
@@ -150,6 +150,18 @@ perfect::CpuTurboState state;
 PERFECT(perfect::get_cpu_turbo_state(&state));
 ```
 
+### High Priority
+
+`perfect` can set high scheduling priority for a process
+
+See [examples/high_priority.cpp](examples/high_priority.cpp)
+
+```c++
+#include "perfect/priority.hpp"
+```
+
+* `Result set_high_priority()`: set the highest possible scheduling priority for the calling process
+
 ### Monitoring
 
 `perfect` can monitor and record GPU activity.
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 4f77d77..ebd23b6 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -43,6 +43,9 @@ target_link_libraries(cpu-turbo perfect)
 add_executable(os-perf os_perf.cpp)
 target_link_libraries(os-perf perfect)
 
+add_executable(high-priority high_priority.cpp)
+target_link_libraries(high-priority perfect)
+
 if(CMAKE_CUDA_COMPILER)
     add_executable(gpu-clocks gpu_clocks.cu)
     target_link_libraries(gpu-clocks perfect)
diff --git a/examples/high_priority.cpp b/examples/high_priority.cpp
new file mode 100644
index 0000000..6204cd9
--- /dev/null
+++ b/examples/high_priority.cpp
@@ -0,0 +1,12 @@
+#include <iostream>
+
+#include "perfect/priority.hpp"
+
+int main(void) {
+  perfect::init();
+
+  PERFECT(perfect::set_high_priority());
+
+  // do things with high process scheduling priority
+
+}
\ No newline at end of file
diff --git a/include/perfect/detail/os/linux.hpp b/include/perfect/detail/os/linux.hpp
index 2b6f0b4..7b4e3a9 100644
--- a/include/perfect/detail/os/linux.hpp
+++ b/include/perfect/detail/os/linux.hpp
@@ -13,6 +13,8 @@
 #include <sys/types.h>
 #include <unistd.h>
 #include <sys/personality.h>
+#include <sys/time.h>
+#include <sys/resource.h>
 
 #include "perfect/result.hpp"
 
@@ -107,6 +109,17 @@ Result set_personality(const int persona) {
   }
   return Result::SUCCESS;
 }
+
+// give the calling process the highest priority
+Result set_high_priority() {
+  if (setpriority(PRIO_PROCESS, 0, -20)) {
+    return from_errno(errno);
+  }
+  return Result::SUCCESS;
+}
+
+
+
 }
 
 } // namespace perfect
\ No newline at end of file
diff --git a/include/perfect/priority.hpp b/include/perfect/priority.hpp
new file mode 100644
index 0000000..358c4ce
--- /dev/null
+++ b/include/perfect/priority.hpp
@@ -0,0 +1,15 @@
+#pragma once
+
+#ifdef __linux__
+#include "detail/os/linux.hpp"
+#else
+#error "unsupported platform"
+#endif
+
+#include "init.hpp"
+
+namespace perfect {
+    Result set_high_priority() {
+        return detail::set_high_priority();
+    }
+}
\ No newline at end of file
diff --git a/tools/perfect.cpp b/tools/perfect.cpp
index 67841de..ee94b81 100644
--- a/tools/perfect.cpp
+++ b/tools/perfect.cpp
@@ -26,6 +26,7 @@
 #include "perfect/detail/os/linux.hpp"
 #include "perfect/drop_caches.hpp"
 #include "perfect/os_perf.hpp"
+#include "perfect/priority.hpp"
 
 // argv should be null-terminated
 // outf and errf are file descriptors to where stdout and stderr should be
@@ -152,6 +153,7 @@ int main(int argc, char **argv) {
   nonstd::optional<bool> cpuTurbo = false;
   nonstd::optional<bool> maxOsPerf = true;
   bool dropCaches = true;
+  bool highPriority = true;
 
   std::vector<std::string> program;
   std::string stdoutPath;
@@ -173,7 +175,8 @@ int main(int argc, char **argv) {
                         .set(aslr, true)
                         .call([&]() { cpuTurbo = nonstd::nullopt; })
                         .call([&]() { maxOsPerf = nonstd::nullopt; })
-                        .set(dropCaches, false));
+                        .set(dropCaches, false)
+                        .set(highPriority, false));
 
   auto modMode = (shieldGroup,
                   option("--no-drop-cache")
@@ -183,6 +186,7 @@ int main(int argc, char **argv) {
                     maxOsPerf = false;
                   }),
                   option("--aslr").set(aslr, true).doc("enable ASLR"),
+                  option("--no-priority").set(highPriority, false).doc("don't set high priority"),
                   option("--cpu-turbo").doc("enable CPU turbo").call([&]() {
                     cpuTurbo = true;
                   }),
@@ -340,6 +344,11 @@ int main(int argc, char **argv) {
     }
   }
 
+  if (highPriority) {
+    std::cerr << "set high priority\n";
+    PERFECT(perfect::set_high_priority());
+  }
+
   // parent should return
   for (int runIter = 0; runIter < iters; ++runIter) {