Host: non-linear constraints

Allows the use of non-linear constraints for CPU resources.

Add API in s4u::Host::set_sharing_policy
- LINEAR(default, shared resources) or NONLINEAR

Example: examples/cpp/exec-cpu-nonlinear

diff --git a/MANIFEST.in b/MANIFEST.in
index c7e3c41..9b183bf 100644 (file)
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -234,6 +234,8 @@ include examples/cpp/exec-async/s4u-exec-async.cpp
 include examples/cpp/exec-async/s4u-exec-async.tesh
 include examples/cpp/exec-basic/s4u-exec-basic.cpp
 include examples/cpp/exec-basic/s4u-exec-basic.tesh
+include examples/cpp/exec-cpu-nonlinear/s4u-exec-cpu-nonlinear.cpp
+include examples/cpp/exec-cpu-nonlinear/s4u-exec-cpu-nonlinear.tesh
 include examples/cpp/exec-dependent/s4u-exec-dependent.cpp
 include examples/cpp/exec-dependent/s4u-exec-dependent.tesh
 include examples/cpp/exec-dvfs/s4u-exec-dvfs.cpp

diff --git a/examples/cpp/CMakeLists.txt b/examples/cpp/CMakeLists.txt
index 94c2f8f..ac25009 100644 (file)
--- a/examples/cpp/CMakeLists.txt
+++ b/examples/cpp/CMakeLists.txt
@@ -70,7 +70,7 @@ foreach (example actor-create actor-daemon actor-exiting actor-join actor-kill
                  energy-exec energy-boot energy-link energy-vm energy-exec-ptask energy-wifi
                  engine-filtering
                  exec-async exec-basic exec-dvfs exec-remote exec-waitany exec-waitfor exec-dependent exec-unassigned
-                 exec-ptask-multicore
+                 exec-ptask-multicore exec-cpu-nonlinear
                  maestro-set
                  mc-bugged1 mc-bugged2 mc-electric-fence mc-failing-assert
                                 network-wifi

diff --git a/examples/cpp/exec-cpu-nonlinear/s4u-exec-cpu-nonlinear.cpp b/examples/cpp/exec-cpu-nonlinear/s4u-exec-cpu-nonlinear.cpp
new file mode 100644 (file)
index 0000000..9331ef9
--- /dev/null
+++ b/examples/cpp/exec-cpu-nonlinear/s4u-exec-cpu-nonlinear.cpp
@@ -0,0 +1,72 @@
+/* Copyright (c) 2010-2021. The SimGrid Team. All rights reserved.          */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+/* This example shows how to simulate a non-linear resource sharing for
+ * CPUs.
+ */
+
+#include <simgrid/s4u.hpp>
+
+namespace sg4 = simgrid::s4u;
+
+XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_network_nonlinear, "Messages specific for this s4u example");
+
+/*************************************************************************************************/
+static void runner()
+{
+  double computation_amount = sg4::this_actor::get_host()->get_speed();
+  int n_task                = 10;
+  std::vector<sg4::ExecPtr> tasks;
+
+  XBT_INFO(
+      "Execute %d tasks of %g flops, should take %d second in a CPU without degradation. It will take the double here.",
+      n_task, computation_amount, n_task);
+  for (int i = 0; i < n_task; i++) {
+    tasks.emplace_back(sg4::this_actor::exec_async(computation_amount));
+  }
+  XBT_INFO("Waiting for all tasks to be done!");
+  for (auto& task : tasks)
+    task->wait();
+
+  XBT_INFO("Finished executing. Goodbye now!");
+}
+/*************************************************************************************************/
+/** @brief Non-linear resource sharing for CPU */
+static double cpu_nonlinear(const sg4::Host* host, double capacity, int n)
+{
+  /* emulates a degradation in link according to the number of flows
+   * totally unrealistic but for learning purposes */
+  capacity = n > 1 ? capacity / 2 : capacity;
+  XBT_INFO("Host %s, %d concurrent tasks, new capacity %lf", host->get_cname(), n, capacity);
+  return capacity;
+}
+
+/** @brief Create a simple 1-host platform */
+static void load_platform()
+{
+  auto* zone        = sg4::create_empty_zone("Zone1");
+  auto* runner_host = zone->create_host("runner", 1e6);
+  runner_host->set_sharing_policy(sg4::Host::SharingPolicy::NONLINEAR,
+                                  std::bind(&cpu_nonlinear, runner_host, std::placeholders::_1, std::placeholders::_2));
+  runner_host->seal();
+  zone->seal();
+
+  /* create actor runner */
+  sg4::Actor::create("runner", runner_host, runner);
+}
+
+/*************************************************************************************************/
+int main(int argc, char* argv[])
+{
+  sg4::Engine e(&argc, argv);
+
+  /* create platform */
+  load_platform();
+
+  /* runs the simulation */
+  e.run();
+
+  return 0;
+}

diff --git a/examples/cpp/exec-cpu-nonlinear/s4u-exec-cpu-nonlinear.tesh b/examples/cpp/exec-cpu-nonlinear/s4u-exec-cpu-nonlinear.tesh
new file mode 100644 (file)
index 0000000..33f529e
--- /dev/null
+++ b/examples/cpp/exec-cpu-nonlinear/s4u-exec-cpu-nonlinear.tesh
@@ -0,0 +1,5 @@
+$ ${bindir:=.}/s4u-exec-cpu-nonlinear "--log=root.fmt:[%10.6r]%e(%i:%a@%h)%e%m%n"
+> [  0.000000] (1:runner@runner) Execute 10 tasks of 1e+06 flops, should take 10 second in a CPU without degradation. It will take the double here.
+> [  0.000000] (1:runner@runner) Waiting for all tasks to be done!
+> [  0.000000] (0:maestro@) Host runner, 10 concurrent tasks, new capacity 500000.000000
+> [ 20.000000] (1:runner@runner) Finished executing. Goodbye now!

diff --git a/include/simgrid/s4u/Host.hpp b/include/simgrid/s4u/Host.hpp
index c39588f..4280793 100644 (file)
--- a/include/simgrid/s4u/Host.hpp
+++ b/include/simgrid/s4u/Host.hpp
@@ -157,6 +157,16 @@ public:
   int get_core_count() const;
   Host* set_core_count(int core_count);
 
+  enum class SharingPolicy { NONLINEAR = 1, LINEAR = 0 };
+  /**
+   * @brief Describes how the CPU is shared between concurrent tasks
+   *
+   * @param policy Sharing policy
+   * @param cb Callback for NONLINEAR policies
+   */
+  Host* set_sharing_policy(SharingPolicy policy, const s4u::NonLinearResourceCb& cb = {});
+  SharingPolicy get_sharing_policy() const;
+
   /** Returns the current computation load (in flops per second)
    *
    * The external load (coming from an availability trace) is not taken in account.

diff --git a/src/s4u/s4u_Host.cpp b/src/s4u/s4u_Host.cpp
index c06d170..575dfad 100644 (file)
--- a/src/s4u/s4u_Host.cpp
+++ b/src/s4u/s4u_Host.cpp
@@ -264,6 +264,17 @@ double Host::get_available_speed() const
   return this->pimpl_cpu_->get_speed_ratio();
 }
 
+Host* Host::set_sharing_policy(SharingPolicy policy, const s4u::NonLinearResourceCb& cb)
+{
+  kernel::actor::simcall([this, policy, &cb] { pimpl_cpu_->set_sharing_policy(policy, cb); });
+  return this;
+}
+
+Host::SharingPolicy Host::get_sharing_policy() const
+{
+  return this->pimpl_cpu_->get_sharing_policy();
+}
+
 int Host::get_core_count() const
 {
   return this->pimpl_cpu_->get_core_count();

diff --git a/src/surf/cpu_interface.cpp b/src/surf/cpu_interface.cpp
index ec58d4a..f6eeaa0 100644 (file)
--- a/src/surf/cpu_interface.cpp
+++ b/src/surf/cpu_interface.cpp
@@ -113,6 +113,31 @@ CpuImpl* CpuImpl::set_core_count(int core_count)
   return this;
 }
 
+void CpuImpl::apply_sharing_policy_cfg() const
+{
+  if (!get_constraint())
+    return;
+
+  kernel::lmm::Constraint::SharingPolicy lmm_policy = kernel::lmm::Constraint::SharingPolicy::SHARED;
+  if (sharing_policy_ == s4u::Host::SharingPolicy::NONLINEAR)
+    lmm_policy = kernel::lmm::Constraint::SharingPolicy::NONLINEAR;
+
+  get_constraint()->set_sharing_policy(lmm_policy, sharing_policy_cb_);
+}
+
+void CpuImpl::set_sharing_policy(s4u::Host::SharingPolicy policy, const s4u::NonLinearResourceCb& cb)
+{
+  xbt_assert(dynamic_cast<CpuTiModel*>(get_model()) == nullptr, "Cannot change sharing policy with CPU:TI model");
+  sharing_policy_    = policy;
+  sharing_policy_cb_ = cb;
+  apply_sharing_policy_cfg();
+}
+
+s4u::Host::SharingPolicy CpuImpl::get_sharing_policy() const
+{
+  return sharing_policy_;
+}
+
 int CpuImpl::get_core_count()
 {
   return core_count_;
@@ -135,6 +160,7 @@ void CpuImpl::seal()
   lmm::System* lmm = get_model()->get_maxmin_system();
   if (dynamic_cast<CpuTiModel*>(get_model()) == nullptr)
     this->set_constraint(lmm->constraint_new(this, core_count_ * speed_per_pstate_.front()));
+  apply_sharing_policy_cfg();
   Resource::seal();
 }
 

diff --git a/src/surf/cpu_interface.hpp b/src/surf/cpu_interface.hpp
index cb672be..3abfd85 100644 (file)
--- a/src/surf/cpu_interface.hpp
+++ b/src/surf/cpu_interface.hpp
@@ -56,6 +56,10 @@ class XBT_PUBLIC CpuImpl : public Resource_T<CpuImpl> {
   int pstate_ = 0;                       /*< Current pstate (index in the speed_per_pstate_)*/
   std::vector<double> speed_per_pstate_; /*< List of supported CPU capacities (pstate related). Not 'const' because VCPU
                                             get modified on migration */
+  s4u::Host::SharingPolicy sharing_policy_ = s4u::Host::SharingPolicy::LINEAR;
+  s4u::NonLinearResourceCb sharing_policy_cb_;
+
+  void apply_sharing_policy_cfg() const;
 
 public:
   /**
@@ -112,6 +116,9 @@ public:
    */
   CpuImpl* set_pstate_speed(const std::vector<double>& speed_per_state);
 
+  void set_sharing_policy(s4u::Host::SharingPolicy policy, const s4u::NonLinearResourceCb& cb);
+  s4u::Host::SharingPolicy get_sharing_policy() const;
+
   /**
    * @brief Execute some quantity of computation
    *