[libfortran] Adjust block size for libgfortran for unformatted reads

Message ID	4b6f06e1-e1ad-9489-5311-5be78b1ae1dd@netcologne.de
State	New
Headers	show Return-Path: <gcc-patches-return-504549-incoming=patchwork.ozlabs.org@gcc.gnu.org> DomainKey-Signature: a=rsa-sha1; c=nofws; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender:to:cc :from:subject:message-id:date:mime-version:content-type; q=dns; s=default; b=SVMvkr/AmcdCTv9UXlds3/ksOAJDNkRFqDbIvqsr6Z5zS1CZvz s65SPBqVzob3CIJPTOqfp1KgD982QL2UB5TP7SeBgPZ6dsoeCCpunGtVBPHIpNJI 1uMz/ZqlHiHcYalIYLCQWTp/wacskeXqgSrC4zVgEToFE8Pm52Y87F9oY= Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk Sender: gcc-patches-owner@gcc.gnu.org To: "fortran@gcc.gnu.org" <fortran@gcc.gnu.org>, gcc-patches <gcc-patches@gcc.gnu.org> Cc: David Edelsohn <dje.gcc@gmail.com> From: Thomas Koenig <tkoenig@netcologne.de> Subject: [patch, libfortran] Adjust block size for libgfortran for unformatted reads Message-ID: <4b6f06e1-e1ad-9489-5311-5be78b1ae1dd@netcologne.de> Date: Sun, 7 Jul 2019 22:13:18 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="------------AE17BC826CB035E6112F5962"
Series	[libfortran] Adjust block size for libgfortran for unformatted reads \| expand [libfortran] Adjust block size for libgfortran for unformatted reads

Index: gcc/fortran/gfortran.texi =================================================================== --- gcc/fortran/gfortran.texi (Revision 273183) +++ gcc/fortran/gfortran.texi (Arbeitskopie) @@ -611,6 +611,8 @@ Malformed environment variables are silently ignor * 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_BUFFER_SIZE_FORMATTED:: Buffer size for formatted files. +* GFORTRAN_BUFFER_SIZE_UNFORMATTED:: Buffer size for unformatted files. @end menu @node TMPDIR @@ -782,6 +784,20 @@ the backtracing, set the variable to @samp{n}, @sa Default is to print a backtrace unless the @option{-fno-backtrace} compile option was used. +@node GFORTRAN_BUFFER_SIZE_FORMATTED +@section @env{GFORTRAN_BUFFER_SIZE_FORMATTED}---Set buffer size for formatted I/O + +The @env{GFORTRAN_BUFFER_SIZE_FORMATTED} environment variable +specifies buffer size in bytes to be used for formatted output. +The default value is 8192. + +@node GFORTRAN_BUFFER_SIZE_UNFORMATTED +@section @env{GFORTRAN_BUFFER_SIZE_UNFORMATTED}---Set buffer size for unformatted I/O + +The @env{GFORTRAN_BUFFER_SIZE_UNFORMATTED} 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 ===================================================================== Index: libgfortran/io/unix.c =================================================================== --- libgfortran/io/unix.c (Revision 273183) +++ libgfortran/io/unix.c (Arbeitskopie) @@ -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 BUFFER_SIZE_FORMATTED_DEFAULT = 8192; +static const int BUFFER_SIZE_UNFORMATTED_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_ 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_ 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_ 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.buffer_size_unformatted > 0) + s->buffer_size = options.buffer_size_unformatted; + else + s->buffer_size = BUFFER_SIZE_UNFORMATTED_DEFAULT; + } + else + { + if (options.buffer_size_formatted > 0) + s->buffer_size = options.buffer_size_formatted; + else + s->buffer_size = BUFFER_SIZE_FORMATTED_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); Index: libgfortran/libgfortran.h =================================================================== --- libgfortran/libgfortran.h (Revision 273183) +++ libgfortran/libgfortran.h (Arbeitskopie) @@ -540,6 +540,7 @@ typedef struct int all_unbuffered, unbuffered_preconnected; int fpe, backtrace; + int buffer_size_unformatted, buffer_size_formatted; } options_t; Index: libgfortran/runtime/environ.c =================================================================== --- libgfortran/runtime/environ.c (Revision 273183) +++ libgfortran/runtime/environ.c (Arbeitskopie) @@ -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_BUFFER_SIZE_UNFORMATTED", 0, &options.buffer_size_unformatted, + init_integer }, + + /* Buffer size for formatted files. */ + { "GFORTRAN_BUFFER_SIZE_FORMATTED", 0, &options.buffer_size_formatted, + init_integer }, + { NULL, 0, NULL, NULL } };

[libfortran] Adjust block size for libgfortran for unformatted reads

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