>From 059268cd8fc9f471e4bedcf80f87d82f7a0bc186 Mon Sep 17 00:00:00 2001 From: =?utf-8?q?P=C3=A1draig=20Brady?= Date: Wed, 14 Jul 2010 09:49:16 +0100 Subject: [PATCH] fadvise: new module providing a simpler interface to posix_fadvise * bootstrap.conf: Include the new module * gl/lib/fadvise.c: Provide a simpler interface to posix_fadvise. (fadvise): Provide hint to the whole file associated with a stream. (fdadvise): Provide hint to the specific portion of a file associated with a file descriptor. * gl/lib/fadvise.h: Rename flags from POSIX_FADV_... to FADVISE_... * gl/modules/fadvise: New file. * m4/jm-macros.m4: Remove the no longer needed posix_fadvise check. * src/sort.c (stream_open): Use the new interface. * src/dd.c (iwrite): Likewise. --- bootstrap.conf | 1 + gl/lib/fadvise.c | 37 +++++++++++++++++++++++++++++++++ gl/lib/fadvise.h | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++ gl/modules/fadvise | 24 +++++++++++++++++++++ m4/jm-macros.m4 | 1 - src/dd.c | 7 +---- src/sort.c | 29 +++++++------------------ 7 files changed, 130 insertions(+), 27 deletions(-) create mode 100644 gl/lib/fadvise.c create mode 100644 gl/lib/fadvise.h create mode 100644 gl/modules/fadvise diff --git a/bootstrap.conf b/bootstrap.conf index fe3974a..31b1212 100644 --- a/bootstrap.conf +++ b/bootstrap.conf @@ -81,6 +81,7 @@ gnulib_modules=" exclude exitfail faccessat + fadvise fchdir fcntl fcntl-safer diff --git a/gl/lib/fadvise.c b/gl/lib/fadvise.c new file mode 100644 index 0000000..e357181 --- /dev/null +++ b/gl/lib/fadvise.c @@ -0,0 +1,37 @@ +/* Declare an access pattern hint for files. + Copyright (C) 2010 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include +#include "fadvise.h" + +#include +#include +#include "ignore-value.h" + +void +fdadvise (int fd, off_t offset, off_t len, int advice) +{ +#if HAVE_POSIX_FADVISE + ignore_value (posix_fadvise (fd, offset, len, advice)); +#endif +} + +void +fadvise (FILE *fp, int advice) +{ + if (fp) + fdadvise (fileno (fp), 0, 0, advice); +} diff --git a/gl/lib/fadvise.h b/gl/lib/fadvise.h new file mode 100644 index 0000000..51b48a0 --- /dev/null +++ b/gl/lib/fadvise.h @@ -0,0 +1,58 @@ +/* Declare an access pattern hint for files. + Copyright (C) 2010 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include +#include +#include +#include + +/* We ignore any errors and these hints are only advisory. + There are a few hints one can provide, which have the + following characteristics on Linux 2.6.31 at least. + + POSIX_FADV_SEQUENTIAL + Doubles the size of read ahead done for file + POSIX_FADV_WILLNEED + _synchronously_ prepopulate the buffer cache with the file + POSIX_FADV_NOREUSE + Could lower priority of data in buffer caches, + but currently does nothing. + POSIX_FADV_DONTNEED + Drop the file from cache. + Note this is automatically done when files are unlinked. */ + +#if HAVE_POSIX_FADVISE +enum { + FADVISE_NORMAL = POSIX_FADV_NORMAL, + FADVISE_SEQUENTIAL = POSIX_FADV_SEQUENTIAL, + FADVISE_NOREUSE = POSIX_FADV_NOREUSE, + FADVISE_DONTNEED = POSIX_FADV_DONTNEED, + FADVISE_WILLNEED = POSIX_FADV_WILLNEED, + FADVISE_RANDOM = POSIX_FADV_RANDOM, +}; +#else +enum { + FADVISE_NORMAL, + FADVISE_SEQUENTIAL, + FADVISE_NOREUSE, + FADVISE_DONTNEED, + FADVISE_WILLNEED, + FADVISE_RANDOM, +}; +#endif + +void fdadvise (int fd, off_t offset, off_t len, int advice); +void fadvise (FILE *fp, int advice); diff --git a/gl/modules/fadvise b/gl/modules/fadvise new file mode 100644 index 0000000..6d7bc78 --- /dev/null +++ b/gl/modules/fadvise @@ -0,0 +1,24 @@ +Description: +Declare an access pattern hint for files. + +Files: +lib/fadvise.c +lib/fadvise.h + +Depends-on: +ignore-value + +configure.ac: +AC_CHECK_FUNCS_ONCE([posix_fadvise]) + +Makefile.am: +lib_SOURCES += fadvise.c fadvise.h + +Include: +"fadvise.h" + +License: +LGPL + +Maintainer: +Pádraig Brady diff --git a/m4/jm-macros.m4 b/m4/jm-macros.m4 index 8711e94..20b9af9 100644 --- a/m4/jm-macros.m4 +++ b/m4/jm-macros.m4 @@ -64,7 +64,6 @@ AC_DEFUN([coreutils_MACROS], LIBS=$coreutils_saved_libs # Used by sort.c. - AC_CHECK_FUNCS_ONCE([posix_fadvise]) AC_CHECK_FUNCS_ONCE([nl_langinfo]) # Used by tail.c. diff --git a/src/dd.c b/src/dd.c index ab8b84c..b6643e2 100644 --- a/src/dd.c +++ b/src/dd.c @@ -27,10 +27,10 @@ #include "system.h" #include "close-stream.h" #include "error.h" +#include "fadvise.h" #include "fd-reopen.h" #include "gethrxtime.h" #include "human.h" -#include "ignore-value.h" #include "long-options.h" #include "quote.h" #include "quotearg.h" @@ -849,12 +849,9 @@ iwrite (int fd, char const *buf, size_t size) posix_fadvise to tell the system not to pollute the buffer cache with this data. Don't bother to diagnose lseek or posix_fadvise failure. */ -#ifdef POSIX_FADV_DONTNEED off_t off = lseek (STDOUT_FILENO, 0, SEEK_CUR); if (0 <= off) - ignore_value (posix_fadvise (STDOUT_FILENO, - off, 0, POSIX_FADV_DONTNEED)); -#endif + fdadvise (STDOUT_FILENO, off, 0, FADVISE_DONTNEED); /* Attempt to ensure that that final block is committed to disk as quickly as possible. */ diff --git a/src/sort.c b/src/sort.c index 7d31878..f79acd9 100644 --- a/src/sort.c +++ b/src/sort.c @@ -30,6 +30,7 @@ #include "system.h" #include "argmatch.h" #include "error.h" +#include "fadvise.h" #include "filevercmp.h" #include "hard-locale.h" #include "hash.h" @@ -856,9 +857,13 @@ create_temp_file (int *pfd, bool survive_fd_exhaustion) return node; } -/* Predeclare an access pattern for input files. - Ignore any errors -- this is only advisory. +/* Return a stream for FILE, opened with mode HOW. A null FILE means + standard output; HOW should be "w". When opening for input, "-" + means standard input. To avoid confusion, do not return file + descriptors STDIN_FILENO, STDOUT_FILENO, or STDERR_FILENO when + opening an ordinary FILE. Return NULL if unsuccessful. + fadvise() is used to specify an access pattern for input files. There are a few hints we could possibly provide, and after careful testing it was decided that specifying POSIX_FADV_SEQUENTIAL was not detrimental @@ -899,24 +904,6 @@ create_temp_file (int *pfd, bool survive_fd_exhaustion) cache immediately after processing. This is done implicitly however when the files are unlinked. */ -static void -fadvise_input (FILE *fp) -{ -#if HAVE_POSIX_FADVISE - if (fp) - { - int fd = fileno (fp); - ignore_value (posix_fadvise (fd, 0, 0, POSIX_FADV_SEQUENTIAL)); - } -#endif -} - -/* Return a stream for FILE, opened with mode HOW. A null FILE means - standard output; HOW should be "w". When opening for input, "-" - means standard input. To avoid confusion, do not return file - descriptors STDIN_FILENO, STDOUT_FILENO, or STDERR_FILENO when - opening an ordinary FILE. Return NULL if unsuccessful. */ - static FILE * stream_open (const char *file, const char *how) { @@ -932,7 +919,7 @@ stream_open (const char *file, const char *how) } else fp = fopen (file, how); - fadvise_input (fp); + fadvise (fp, FADVISE_SEQUENTIAL); return fp; } return fopen (file, how); -- 1.6.2.5