Added an option to configure for disabling the use of posix_fadvise completely. Also check the OS and kernel version. Use posix_fadvise only if we're running on Linux and a kernel from the 2.6.x series or newer.

ChangeLog

@@ -15,7 +15,10 @@
 
 	* mkvmerge: new feature: Use the posix_fadvise function on *nix
 	systems. This results in a considerable speed up for the whole
-	muxing process.
+	muxing process. As the function call seems to be buggy on at least
+	Linux kernels 2.4.x it can be disabled completely during
+	configure. It will only be used on Linux with a kernel from the
+	2.6.x series or newer.
 
 2005-02-01  Moritz Bunkus  <moritz@bunkus.org>
 

configure.in

@@ -292,6 +292,11 @@ fi
 dnl
 dnl Check for posix_fadvise and its definitions
 dnl
+AC_ARG_ENABLE(posix-fadvise,
+  [  --disable-posix-fadvise do not use posix_fadvise (auto)],,
+  [enable_posix_fadvise=yes])
+
+if test x"$enable_posix_fadvise" != "xno" ; then 
   AC_CACHE_CHECK([for posix_fadvise], [ac_cv_posix_fadvise],[
     ac_cv_posix_fadvise="no"
     AC_LANG_PUSH(C++)
@@ -306,7 +311,7 @@ dnl
   if test x"$ac_cv_posix_fadvise" = "xyes" ; then
     AC_DEFINE([HAVE_POSIX_FADVISE], 1, [define if posix_advise and its definitions are available])
   fi
-
+fi
 
 dnl
 dnl Test for libiconv

src/common/mm_io.cpp

@@ -19,6 +19,7 @@
 #include <errno.h>
 #if HAVE_POSIX_FADVISE
 # include <fcntl.h>
+# include <sys/utsname.h>
 #endif
 #include <string.h>
 #include <stdarg.h>
@@ -41,6 +42,7 @@ using namespace std;
 # if HAVE_POSIX_FADVISE
 static const unsigned long read_using_willneed = 16 * 1024 * 1024;
 static const unsigned long write_before_dontneed = 8 * 1024 * 1024;
+bool mm_file_io_c::use_posix_fadvise = false;
 # endif
 
 mm_file_io_c::mm_file_io_c(const string &path,
@@ -93,8 +95,9 @@ mm_file_io_c::mm_file_io_c(const string &path,
     throw error_c(mxsprintf("Error opening file %s", path.c_str()));
 
 # if HAVE_POSIX_FADVISE
-  if (0 != posix_fadvise(fileno((FILE *)file), 0, read_using_willneed,
-                         advise))
+  if (use_posix_fadvise &&
+      (0 != posix_fadvise(fileno((FILE *)file), 0, read_using_willneed,
+                          advise)))
     mxerror("mm_file_io_c: Could not fadvise file '%s' (errno = %d, %s)\n",
             path.c_str(), errno, strerror(errno));
 # endif
@@ -133,7 +136,7 @@ mm_file_io_c::write(const void *buffer,
 
 # if HAVE_POSIX_FADVISE
   write_count += bwritten;
-  if (write_count > write_before_dontneed) {
+  if (use_posix_fadvise && (write_count > write_before_dontneed)) {
     uint64 pos = getFilePointer();
     write_count = 0;
     if (0 != posix_fadvise(fileno((FILE *)file), 0, pos, POSIX_FADV_DONTNEED))
@@ -153,7 +156,7 @@ mm_file_io_c::read(void *buffer,
   bread = fread(buffer, 1, size, (FILE *)file); 
 
 # if HAVE_POSIX_FADVISE
-  if (bread >= 0) {
+  if (use_posix_fadvise && (0 <= bread)) {
     read_count += bread;
     if (read_count > read_using_willneed) {
       uint64 pos = getFilePointer();
@@ -189,6 +192,31 @@ mm_file_io_c::truncate(int64_t pos) {
   return ftruncate(fileno((FILE *)file), pos);
 }
 
+/** \brief OS and kernel dependant setup
+
+   The \c posix_fadvise call can improve read/write performance a lot.
+   Unfortunately it is pretty new and a buggy on a couple of Linux kernels
+   in the 2.4.x series. So only enable its usage for 2.6.x kernels.
+*/
+void
+mm_file_io_c::setup() {
+# if HAVE_POSIX_FADVISE
+  struct utsname un;
+
+  use_posix_fadvise = false;
+  if ((0 == uname(&un)) && !strcasecmp(un.sysname, "Linux")) {
+    vector<string> versions;
+    int major, minor;
+
+    versions = split(un.release, ".");
+    if ((2 <= versions.size()) &&
+        parse_int(versions[0], major) && parse_int(versions[1], minor) &&
+        ((2 < major) || (6 <= minor)))
+      use_posix_fadvise = true;
+  }
+# endif // HAVE_POSIX_FADVISE
+}
+
 #else // SYS_WINDOWS
 
 HANDLE
@@ -359,6 +387,10 @@ mm_file_io_c::truncate(int64_t pos) {
   return -1;
 }
 
+void
+mm_file_io_c::setup() {
+}
+
 #endif // SYS_UNIX
 
 mm_file_io_c::~mm_file_io_c() {

src/common/mm_io.h

@@ -91,6 +91,7 @@ protected:
 #endif
 #if HAVE_POSIX_FADVISE
   unsigned long read_count, write_count;
+  static bool use_posix_fadvise;
 #endif
   string file_name;
   void *file;
@@ -111,6 +112,8 @@ public:
   }
 
   virtual int truncate(int64_t pos);
+
+  static void setup();
 };
 
 class MTX_DLL_API mm_proxy_io_c: public mm_io_c {

src/extract/mkvextract.cpp

@@ -379,6 +379,7 @@ main(int argc,
   textdomain("mkvtoolnix");
 #endif
 
+  mm_file_io_c::setup();
   srand(time(NULL));
   utf8_init("");
 

src/info/mkvinfo.cpp

@@ -1964,6 +1964,7 @@ setup() {
   textdomain("mkvtoolnix");
 #endif
 
+  mm_file_io_c::setup();
   cc_local_utf8 = utf8_init("");
   init_cc_stdio();
 

src/merge/output_control.cpp

@@ -1921,6 +1921,7 @@ setup() {
   signal(SIGINT, sighandler);
 #endif
 
+  mm_file_io_c::setup();
   srand(time(NULL));
   cc_local_utf8 = utf8_init("");
   init_cc_stdio();

src/mmg/mmg.cpp

@@ -1872,6 +1872,7 @@ mmg_app::OnInit() {
   uint32_t i;
   wxString k, v;
 
+  mm_file_io_c::setup();
   cc_local_utf8 = utf8_init("");
   xml_element_map_init();