Add alternative to remap() in PageStore when not available.

[simgrid.git] / src / mc / PageStore.cpp

diff --git a/src/mc/PageStore.cpp b/src/mc/PageStore.cpp
index 5be3176..78f28e6 100644 (file)
--- a/src/mc/PageStore.cpp
+++ b/src/mc/PageStore.cpp
@@ -5,19 +5,20 @@
  * under the terms of the license (GNU LGPL) which comes with this package. */
 
 #include <unistd.h>
-#include <string.h> // memcpy, memcp
+#include <string.h> // memcpy, memcmp
 
 #include <sys/mman.h>
+#ifdef __FreeBSD__
+# define MAP_POPULATE MAP_PREFAULT_READ
+#endif
 
-#include <boost/foreach.hpp>
+#include <xbt/base.h>
+#include <xbt/log.h>
+#include <xbt/sysdep.h>
 
-#include <xbt.h>
+#include "src/mc/PageStore.hpp"
 
-#include "PageStore.hpp"
-
-#include "mc_mmu.h"
-
-extern "C" {
+#include "src/mc/mc_mmu.h"
 
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_page_snapshot, mc,
                                 "Logging specific to mc_page_snapshot");
@@ -25,7 +26,7 @@ XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_page_snapshot, mc,
 namespace simgrid {
 namespace mc {
 
-/** @brief Compte a hash for the given memory page
+/** @brief Compute a hash for the given memory page
  *
  *  The page is used before inserting the page in the page store
  *  in order to find duplicate of this page in the page store.
@@ -41,24 +42,22 @@ PageStore::hash_type mc_hash_page(const void* data)
 
   // This djb2:
   std::uint64_t hash = 5381;
-  for (std::size_t i = 0; i != n; ++i) {
+  for (std::size_t i = 0; i != n; ++i)
     hash = ((hash << 5) + hash) + values[i];
-  }
   return hash;
 }
 
 // ***** snapshot_page_manager
 
 PageStore::PageStore(size_t size) :
-  memory_(NULL), capacity_(0), top_index_(0)
+  memory_(nullptr), capacity_(0), top_index_(0)
 {
   // Using mmap in order to be able to expand the region
   // by relocating it somewhere else in the virtual memory
   // space:
-  void* memory = ::mmap(NULL, size << xbt_pagebits, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_POPULATE, -1, 0);
-  if (memory == MAP_FAILED) {
+  void* memory = ::mmap(nullptr, size << xbt_pagebits, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_POPULATE, -1, 0);
+  if (memory == MAP_FAILED)
     xbt_die("Could not mmap initial snapshot pages.");
-  }
 
   this->top_index_ = 0;
   this->capacity_ = size;
@@ -75,13 +74,46 @@ void PageStore::resize(std::size_t size)
 {
   size_t old_bytesize = this->capacity_ << xbt_pagebits;
   size_t new_bytesize = size << xbt_pagebits;
+  void *new_memory;
 
   // Expand the memory region by moving it into another
   // virtual memory address if necessary:
-  void* new_memory = mremap(this->memory_, old_bytesize, new_bytesize, MREMAP_MAYMOVE);
-  if (new_memory == MAP_FAILED) {
+#if HAVE_MREMAP
+  new_memory = mremap(this->memory_, old_bytesize, new_bytesize, MREMAP_MAYMOVE);
+  if (new_memory == MAP_FAILED)
     xbt_die("Could not mremap snapshot pages.");
+#else
+  if (new_bytesize > old_bytesize) {
+    // Grow: first try to add new space after current map
+    new_memory = mmap((char *)this->memory_ + old_bytesize,
+                      new_bytesize-old_bytesize,
+                      PROT_READ|PROT_WRITE,
+                      MAP_PRIVATE|MAP_ANONYMOUS|MAP_POPULATE,
+                      -1, 0);
+    if (new_memory == MAP_FAILED)
+      xbt_die("Could not mremap snapshot pages.");
+    // Check if expanding worked
+    if (new_memory != (char *)this->memory_ + old_bytesize) {
+      // New memory segment could not be put at the end of this->memory_,
+      // so cancel this one and try to rellocate everything and copy data
+      munmap(new_memory, new_bytesize-old_bytesize);
+      new_memory = mmap(nullptr,
+                        new_bytesize,
+                        PROT_READ|PROT_WRITE,
+                        MAP_PRIVATE|MAP_ANONYMOUS|MAP_POPULATE,
+                        -1, 0);
+      if (new_memory == MAP_FAILED)
+        xbt_die("Could not mremap snapshot pages.");
+      memcpy(new_memory, this->memory_, old_bytesize);
+      munmap(this->memory_, old_bytesize);
+    }
+  }
+  else {
+    // We don't have functions to shrink a mapping, so leave memory as
+    // it is for now
+    new_memory = this->memory_;
   }
+#endif
 
   this->capacity_ = size;
   this->memory_ = new_memory;
@@ -97,10 +129,9 @@ std::size_t PageStore::alloc_page()
   if (this->free_pages_.empty()) {
 
     // Expand the region:
-    if (this->top_index_ == this->capacity_) {
+    if (this->top_index_ == this->capacity_)
       // All the pages are allocated, we need add more pages:
       this->resize(2 * this->capacity_);
-    }
 
     // Use a page from the top:
     return this->top_index_++;
@@ -137,7 +168,7 @@ std::size_t PageStore::store_page(void* page)
 
   // Try to find a duplicate in set of pages with the same hash:
   page_set_type& page_set = this->hash_index_[hash];
-  BOOST_FOREACH (size_t pageno, page_set) {
+  for (size_t pageno : page_set) {
     const void* snapshot_page = this->get_page(pageno);
     if (memcmp(page, snapshot_page, xbt_pagesize) == 0) {
 
@@ -173,7 +204,7 @@ std::size_t PageStore::store_page(void* page)
 
 #include <memory>
 
-#include "mc/PageStore.hpp"
+#include "src/mc/PageStore.hpp"
 
 static int value = 0;
 
@@ -184,11 +215,9 @@ static void new_content(void* data, std::size_t size)
 
 static void* getpage()
 {
-  return mmap(NULL, getpagesize(), PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+  return mmap(nullptr, getpagesize(), PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
 }
 
-extern "C" {
-
 XBT_TEST_SUITE("mc_page_store", "Page store");
 
 XBT_TEST_UNIT("base", test_mc_page_store, "Test adding/removing pages in the store")
@@ -237,8 +266,4 @@ XBT_TEST_UNIT("base", test_mc_page_store, "Test adding/removing pages in the sto
   xbt_test_assert(store->size()==2, "Bad size");
 }
 
-}
-
 #endif /* SIMGRID_TEST */
-
-}