backport: re PR libfortran/91030 (Poor performance of I/O -fconvert=big-endian)

2019-07-23  Thomas König  <tkoenig@gcc.gnu.org>

	Backport from trunk
	PR libfortran/91030
	* gfortran.texi (GFORTRAN_FORMATTED_BUFFER_SIZE): Document.
	(GFORTRAN_UNFORMATTED_BUFFER_SIZE): Likewise.

2019-07-23  Thomas König  <tkoenig@gcc.gnu.org>

	Backport from trunk
	PR libfortran/91030
	* io/unix.c (BUFFER_SIZE): Delete.
	(BUFFER_FORMATTED_SIZE_DEFAULT): New variable.
	(BUFFER_UNFORMATTED_SIZE_DEFAULT): New variable.
	(unix_stream): Add buffer_size.
	(buf_read): Use s->buffer_size instead of BUFFER_SIZE.
	(buf_write): Likewise.
	(buf_init): Add argument unformatted.  Handle block sizes
	for unformatted vs. formatted, using defaults if provided.
	(fd_to_stream): Add argument unformatted in call to buf_init.
	* libgfortran.h (options_t): Add buffer_size_formatted and
	buffer_size_unformatted.
	* runtime/environ.c (variable_table): Add
	GFORTRAN_UNFORMATTED_BUFFER_SIZE and
	GFORTRAN_FORMATTED_BUFFER_SIZE.

From-SVN: r273727

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index 13dccac7ac2002a9e67b74508c7005cfe475b680..7901430a1945a66f72cc272458e7f5e04ee2d72e 100644 (file)
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,10 @@
+2019-07-23  Thomas König  <tkoenig@gcc.gnu.org>
+
+       Backport from trunk
+       PR libfortran/91030
+       * gfortran.texi (GFORTRAN_FORMATTED_BUFFER_SIZE): Document.
+       (GFORTRAN_UNFORMATTED_BUFFER_SIZE): Likewise.
+
 2019-07-07  Paul Thomas  <pault@gcc.gnu.org>
 
        Backport from mainline

diff --git a/gcc/fortran/gfortran.texi b/gcc/fortran/gfortran.texi
index 76c1f2da7a64301dc789cb01b55f517a57bc71c5..6a8337a4bbfe21af92e75e0fbf13c90d3696cde3 100644 (file)
--- a/gcc/fortran/gfortran.texi
+++ b/gcc/fortran/gfortran.texi
@@ -611,6 +611,8 @@ Malformed environment variables are silently ignored.
 * GFORTRAN_LIST_SEPARATOR::  Separator for list output
 * GFORTRAN_CONVERT_UNIT::  Set endianness for unformatted I/O
 * GFORTRAN_ERROR_BACKTRACE:: Show backtrace on run-time errors
+* GFORTRAN_FORMATTED_BUFFER_SIZE:: Buffer size for formatted files.
+* GFORTRAN_UNFORMATTED_BUFFER_SIZE:: Buffer size for unformatted files.
 @end menu
 
 @node TMPDIR
@@ -782,6 +784,20 @@ the backtracing, set the variable to @samp{n}, @samp{N}, @samp{0}.
 Default is to print a backtrace unless the @option{-fno-backtrace}
 compile option was used.
 
+@node GFORTRAN_FORMATTED_BUFFER_SIZE
+@section @env{GFORTRAN_FORMATTED_BUFFER_SIZE}---Set buffer size for formatted I/O
+
+The @env{GFORTRAN_FORMATTED_BUFFER_SIZE} environment variable
+specifies buffer size in bytes to be used for formatted output.
+The default value is 8192.
+
+@node GFORTRAN_UNFORMATTED_BUFFER_SIZE
+@section @env{GFORTRAN_UNFORMATTED_BUFFER_SIZE}---Set buffer size for unformatted I/O
+
+The @env{GFORTRAN_UNFORMATTED_BUFFER_SIZE} environment variable
+specifies buffer size in bytes to be used for unformatted output.
+The default value is 131072.
+
 @c =====================================================================
 @c PART II: LANGUAGE REFERENCE
 @c =====================================================================

diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog
index fc354f9045eaa5b39cee0be9ca9458ef996f4328..d2fd578a2d4b7ede07d60846c07606442e18076a 100644 (file)
--- a/libgfortran/ChangeLog
+++ b/libgfortran/ChangeLog
@@ -1,3 +1,22 @@
+2019-07-23  Thomas König  <tkoenig@gcc.gnu.org>
+
+       Backport from trunk
+       PR libfortran/91030
+       * io/unix.c (BUFFER_SIZE): Delete.
+       (BUFFER_FORMATTED_SIZE_DEFAULT): New variable.
+       (BUFFER_UNFORMATTED_SIZE_DEFAULT): New variable.
+       (unix_stream): Add buffer_size.
+       (buf_read): Use s->buffer_size instead of BUFFER_SIZE.
+       (buf_write): Likewise.
+       (buf_init): Add argument unformatted.  Handle block sizes
+       for unformatted vs. formatted, using defaults if provided.
+       (fd_to_stream): Add argument unformatted in call to buf_init.
+       * libgfortran.h (options_t): Add buffer_size_formatted and
+       buffer_size_unformatted.
+       * runtime/environ.c (variable_table): Add
+       GFORTRAN_UNFORMATTED_BUFFER_SIZE and
+       GFORTRAN_FORMATTED_BUFFER_SIZE.
+
 2019-05-20  Janne Blomqvist  <jb@gcc.gnu.org>
 
        Backport from trunk

diff --git a/libgfortran/io/unix.c b/libgfortran/io/unix.c
index c2fc674cc8339e09ab034a3a4ea0d6db8a8aa377..42792976c4b4c16acec661758ac9c09340227489 100644 (file)
--- a/libgfortran/io/unix.c
+++ b/libgfortran/io/unix.c
@@ -193,7 +193,8 @@ fallback_access (const char *path, int mode)
 
 /* Unix and internal stream I/O module */
 
-static const int BUFFER_SIZE = 8192;
+static const int FORMATTED_BUFFER_SIZE_DEFAULT = 8192;
+static const int UNFORMATTED_BUFFER_SIZE_DEFAULT = 128*1024;
 
 typedef struct
 {
@@ -205,6 +206,7 @@ typedef struct
   gfc_offset file_length;      /* Length of the file. */
 
   char *buffer;                 /* Pointer to the buffer.  */
+  ssize_t buffer_size;           /* Length of the buffer.  */
   int fd;                       /* The POSIX file descriptor.  */
 
   int active;                  /* Length of valid bytes in the buffer */
@@ -592,9 +594,9 @@ buf_read (unix_stream *s, void *buf, ssize_t nbyte)
           && raw_seek (s, new_logical, SEEK_SET) < 0)
         return -1;
       s->buffer_offset = s->physical_offset = new_logical;
-      if (to_read <= BUFFER_SIZE/2)
+      if (to_read <= s->buffer_size/2)
         {
-          did_read = raw_read (s, s->buffer, BUFFER_SIZE);
+          did_read = raw_read (s, s->buffer, s->buffer_size);
          if (likely (did_read >= 0))
            {
              s->physical_offset += did_read;
@@ -632,11 +634,11 @@ buf_write (unix_stream *s, const void *buf, ssize_t nbyte)
     s->buffer_offset = s->logical_offset;
 
   /* Does the data fit into the buffer?  As a special case, if the
-     buffer is empty and the request is bigger than BUFFER_SIZE/2,
+     buffer is empty and the request is bigger than s->buffer_size/2,
      write directly. This avoids the case where the buffer would have
      to be flushed at every write.  */
-  if (!(s->ndirty == 0 && nbyte > BUFFER_SIZE/2)
-      && s->logical_offset + nbyte <= s->buffer_offset + BUFFER_SIZE
+  if (!(s->ndirty == 0 && nbyte > s->buffer_size/2)
+      && s->logical_offset + nbyte <= s->buffer_offset + s->buffer_size
       && s->buffer_offset <= s->logical_offset
       && s->buffer_offset + s->ndirty >= s->logical_offset)
     {
@@ -651,7 +653,7 @@ buf_write (unix_stream *s, const void *buf, ssize_t nbyte)
          the request is bigger than the buffer size, write directly
          bypassing the buffer.  */
       buf_flush (s);
-      if (nbyte <= BUFFER_SIZE/2)
+      if (nbyte <= s->buffer_size/2)
         {
           memcpy (s->buffer, buf, nbyte);
           s->buffer_offset = s->logical_offset;
@@ -688,7 +690,7 @@ buf_write (unix_stream *s, const void *buf, ssize_t nbyte)
 static int
 buf_markeor (unix_stream *s)
 {
-  if (s->unbuffered || s->ndirty >= BUFFER_SIZE / 2)
+  if (s->unbuffered || s->ndirty >= s->buffer_size / 2)
     return buf_flush (s);
   return 0;
 }
@@ -765,11 +767,32 @@ static const struct stream_vtable buf_vtable = {
 };
 
 static int
-buf_init (unix_stream *s)
+buf_init (unix_stream *s, bool unformatted)
 {
   s->st.vptr = &buf_vtable;
 
-  s->buffer = xmalloc (BUFFER_SIZE);
+  /* Try to guess a good value for the buffer size.  For formatted
+     I/O, we use so many CPU cycles converting the data that there is
+     more sense in converving memory and especially cache.  For
+     unformatted, a bigger block can have a large impact in some
+     environments.  */
+
+  if (unformatted)
+    {
+      if (options.unformatted_buffer_size > 0)
+       s->buffer_size = options.unformatted_buffer_size;
+      else
+       s->buffer_size = UNFORMATTED_BUFFER_SIZE_DEFAULT;
+    }
+  else
+    {
+      if (options.formatted_buffer_size > 0)
+       s->buffer_size = options.formatted_buffer_size;
+      else
+       s->buffer_size = FORMATTED_BUFFER_SIZE_DEFAULT;
+    }
+
+  s->buffer = xmalloc (s->buffer_size);
   return 0;
 }
 
@@ -1120,13 +1143,13 @@ fd_to_stream (int fd, bool unformatted)
           (s->fd == STDIN_FILENO 
            || s->fd == STDOUT_FILENO 
            || s->fd == STDERR_FILENO)))
-    buf_init (s);
+    buf_init (s, unformatted);
   else
     {
       if (unformatted)
        {
          s->unbuffered = true;
-         buf_init (s);
+         buf_init (s, unformatted);
        }
       else
        raw_init (s);

diff --git a/libgfortran/libgfortran.h b/libgfortran/libgfortran.h
index 433b204abdac70987d083a7578aede181912d36a..c0db96f02a8aa8fca5c5a6a115f283caf1d12972 100644 (file)
--- a/libgfortran/libgfortran.h
+++ b/libgfortran/libgfortran.h
@@ -540,6 +540,7 @@ typedef struct
 
   int all_unbuffered, unbuffered_preconnected;
   int fpe, backtrace;
+  int unformatted_buffer_size, formatted_buffer_size;
 }
 options_t;
 

diff --git a/libgfortran/runtime/environ.c b/libgfortran/runtime/environ.c
index e3e7d2499d7c415c6d3555453e8d68e1f393a3a3..5817d1997999defcd7f37a382d85db32fc7448e4 100644 (file)
--- a/libgfortran/runtime/environ.c
+++ b/libgfortran/runtime/environ.c
@@ -198,6 +198,14 @@ static variable variable_table[] = {
   /* Print out a backtrace if possible on runtime error */
   { "GFORTRAN_ERROR_BACKTRACE", -1, &options.backtrace, init_boolean },
 
+  /* Buffer size for unformatted files.  */
+  { "GFORTRAN_UNFORMATTED_BUFFER_SIZE", 0, &options.unformatted_buffer_size,
+    init_integer },
+
+  /* Buffer size for formatted files.  */
+  { "GFORTRAN_FORMATTED_BUFFER_SIZE", 0, &options.formatted_buffer_size,
+    init_integer },
+
   { NULL, 0, NULL, NULL }
 };