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* [gcc r14-1568] libstdc++: Also use sendfile for big files
@ 2023-06-06 11:35 Jonathan Wakely
0 siblings, 0 replies; only message in thread
From: Jonathan Wakely @ 2023-06-06 11:35 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:f80a8b42296265bb868a48592a2bd1fdaa2a3d8a
commit r14-1568-gf80a8b42296265bb868a48592a2bd1fdaa2a3d8a
Author: Jannik Glückert <jannik.glueckert@gmail.com>
Date: Mon Mar 6 20:52:08 2023 +0100
libstdc++: Also use sendfile for big files
We were previously only using sendfile for files smaller than 2GB, as
sendfile needs to be called repeatedly for files bigger than that.
Some quick numbers, copying a 16GB file, average of 10 repetitions:
old:
real: 13.4s
user: 0.14s
sys : 7.43s
new:
real: 8.90s
user: 0.00s
sys : 3.68s
libstdc++-v3/ChangeLog:
* acinclude.m4 (_GLIBCXX_HAVE_LSEEK): Define.
* config.h.in: Regenerate.
* configure: Regenerate.
* src/filesystem/ops-common.h (copy_file_sendfile): Define new
function for sendfile logic. Loop to support large files. Skip
zero-length files.
(do_copy_file): Use it.
Signed-off-by: Jannik Glückert <jannik.glueckert@gmail.com>
Diff:
---
libstdc++-v3/acinclude.m4 | 51 ++++++++-----
libstdc++-v3/config.h.in | 3 +
libstdc++-v3/configure | 127 ++++++++++++++++++++++---------
libstdc++-v3/src/filesystem/ops-common.h | 73 +++++++++++-------
4 files changed, 170 insertions(+), 84 deletions(-)
diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 6ae141b8c20..1920444e5cd 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -4956,6 +4956,7 @@ dnl _GLIBCXX_USE_FCHMOD
dnl _GLIBCXX_USE_FCHMODAT
dnl _GLIBCXX_USE_SENDFILE
dnl HAVE_LINK
+dnl HAVE_LSEEK
dnl HAVE_READLINK
dnl HAVE_SYMLINK
dnl
@@ -5091,25 +5092,6 @@ dnl
if test $glibcxx_cv_fchmodat = yes; then
AC_DEFINE(_GLIBCXX_USE_FCHMODAT, 1, [Define if fchmodat is available in <sys/stat.h>.])
fi
-dnl
- AC_CACHE_CHECK([for sendfile that can copy files],
- glibcxx_cv_sendfile, [dnl
- case "${target_os}" in
- gnu* | linux* | solaris* | uclinux*)
- GCC_TRY_COMPILE_OR_LINK(
- [#include <sys/sendfile.h>],
- [sendfile(1, 2, (off_t*)0, sizeof 1);],
- [glibcxx_cv_sendfile=yes],
- [glibcxx_cv_sendfile=no])
- ;;
- *)
- glibcxx_cv_sendfile=no
- ;;
- esac
- ])
- if test $glibcxx_cv_sendfile = yes; then
- AC_DEFINE(_GLIBCXX_USE_SENDFILE, 1, [Define if sendfile is available in <sys/sendfile.h>.])
- fi
dnl
AC_CACHE_CHECK([for link],
glibcxx_cv_link, [dnl
@@ -5122,6 +5104,18 @@ dnl
if test $glibcxx_cv_link = yes; then
AC_DEFINE(HAVE_LINK, 1, [Define if link is available in <unistd.h>.])
fi
+dnl
+ AC_CACHE_CHECK([for lseek],
+ glibcxx_cv_lseek, [dnl
+ GCC_TRY_COMPILE_OR_LINK(
+ [#include <unistd.h>],
+ [lseek(1, 0, SEEK_SET);],
+ [glibcxx_cv_lseek=yes],
+ [glibcxx_cv_lseek=no])
+ ])
+ if test $glibcxx_cv_lseek = yes; then
+ AC_DEFINE(HAVE_LSEEK, 1, [Define if lseek is available in <unistd.h>.])
+ fi
dnl
AC_CACHE_CHECK([for readlink],
glibcxx_cv_readlink, [dnl
@@ -5158,6 +5152,25 @@ dnl
if test $glibcxx_cv_truncate = yes; then
AC_DEFINE(HAVE_TRUNCATE, 1, [Define if truncate is available in <unistd.h>.])
fi
+dnl
+ AC_CACHE_CHECK([for sendfile that can copy files],
+ glibcxx_cv_sendfile, [dnl
+ case "${target_os}" in
+ gnu* | linux* | solaris* | uclinux*)
+ GCC_TRY_COMPILE_OR_LINK(
+ [#include <sys/sendfile.h>],
+ [sendfile(1, 2, (off_t*)0, sizeof 1);],
+ [glibcxx_cv_sendfile=yes],
+ [glibcxx_cv_sendfile=no])
+ ;;
+ *)
+ glibcxx_cv_sendfile=no
+ ;;
+ esac
+ ])
+ if test $glibcxx_cv_sendfile = yes && test $glibcxx_cv_lseek = yes; then
+ AC_DEFINE(_GLIBCXX_USE_SENDFILE, 1, [Define if sendfile is available in <sys/sendfile.h>.])
+ fi
dnl
AC_CACHE_CHECK([for fdopendir],
glibcxx_cv_fdopendir, [dnl
diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in
index 5a95853cbbe..99ce682670e 100644
--- a/libstdc++-v3/config.h.in
+++ b/libstdc++-v3/config.h.in
@@ -254,6 +254,9 @@
/* Define to 1 if you have the `logl' function. */
#undef HAVE_LOGL
+/* Define if lseek is available in <unistd.h>. */
+#undef HAVE_LSEEK
+
/* Define to 1 if you have the <machine/endian.h> header file. */
#undef HAVE_MACHINE_ENDIAN_H
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 70d169cf64b..50a7c30665b 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -71005,29 +71005,27 @@ $as_echo "$glibcxx_cv_fchmodat" >&6; }
$as_echo "#define _GLIBCXX_USE_FCHMODAT 1" >>confdefs.h
fi
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sendfile that can copy files" >&5
-$as_echo_n "checking for sendfile that can copy files... " >&6; }
-if ${glibcxx_cv_sendfile+:} false; then :
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking for link" >&5
+$as_echo_n "checking for link... " >&6; }
+if ${glibcxx_cv_link+:} false; then :
$as_echo_n "(cached) " >&6
else
- case "${target_os}" in
- gnu* | linux* | solaris* | uclinux*)
- if test x$gcc_no_link = xyes; then
+ if test x$gcc_no_link = xyes; then
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
-#include <sys/sendfile.h>
+#include <unistd.h>
int
main ()
{
-sendfile(1, 2, (off_t*)0, sizeof 1);
+link("", "");
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
- glibcxx_cv_sendfile=yes
+ glibcxx_cv_link=yes
else
- glibcxx_cv_sendfile=no
+ glibcxx_cv_link=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
else
@@ -71036,40 +71034,35 @@ else
fi
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
-#include <sys/sendfile.h>
+#include <unistd.h>
int
main ()
{
-sendfile(1, 2, (off_t*)0, sizeof 1);
+link("", "");
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_link "$LINENO"; then :
- glibcxx_cv_sendfile=yes
+ glibcxx_cv_link=yes
else
- glibcxx_cv_sendfile=no
+ glibcxx_cv_link=no
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
- ;;
- *)
- glibcxx_cv_sendfile=no
- ;;
- esac
fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_sendfile" >&5
-$as_echo "$glibcxx_cv_sendfile" >&6; }
- if test $glibcxx_cv_sendfile = yes; then
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_link" >&5
+$as_echo "$glibcxx_cv_link" >&6; }
+ if test $glibcxx_cv_link = yes; then
-$as_echo "#define _GLIBCXX_USE_SENDFILE 1" >>confdefs.h
+$as_echo "#define HAVE_LINK 1" >>confdefs.h
fi
- { $as_echo "$as_me:${as_lineno-$LINENO}: checking for link" >&5
-$as_echo_n "checking for link... " >&6; }
-if ${glibcxx_cv_link+:} false; then :
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking for lseek" >&5
+$as_echo_n "checking for lseek... " >&6; }
+if ${glibcxx_cv_lseek+:} false; then :
$as_echo_n "(cached) " >&6
else
if test x$gcc_no_link = xyes; then
@@ -71079,15 +71072,15 @@ else
int
main ()
{
-link("", "");
+lseek(1, 0, SEEK_SET);
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
- glibcxx_cv_link=yes
+ glibcxx_cv_lseek=yes
else
- glibcxx_cv_link=no
+ glibcxx_cv_lseek=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
else
@@ -71100,26 +71093,26 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
int
main ()
{
-link("", "");
+lseek(1, 0, SEEK_SET);
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_link "$LINENO"; then :
- glibcxx_cv_link=yes
+ glibcxx_cv_lseek=yes
else
- glibcxx_cv_link=no
+ glibcxx_cv_lseek=no
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_link" >&5
-$as_echo "$glibcxx_cv_link" >&6; }
- if test $glibcxx_cv_link = yes; then
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_lseek" >&5
+$as_echo "$glibcxx_cv_lseek" >&6; }
+ if test $glibcxx_cv_lseek = yes; then
-$as_echo "#define HAVE_LINK 1" >>confdefs.h
+$as_echo "#define HAVE_LSEEK 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for readlink" >&5
@@ -71286,6 +71279,68 @@ $as_echo "$glibcxx_cv_truncate" >&6; }
$as_echo "#define HAVE_TRUNCATE 1" >>confdefs.h
+ fi
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sendfile that can copy files" >&5
+$as_echo_n "checking for sendfile that can copy files... " >&6; }
+if ${glibcxx_cv_sendfile+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ case "${target_os}" in
+ gnu* | linux* | solaris* | uclinux*)
+ if test x$gcc_no_link = xyes; then
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+#include <sys/sendfile.h>
+int
+main ()
+{
+sendfile(1, 2, (off_t*)0, sizeof 1);
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+ glibcxx_cv_sendfile=yes
+else
+ glibcxx_cv_sendfile=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+else
+ if test x$gcc_no_link = xyes; then
+ as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
+fi
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+#include <sys/sendfile.h>
+int
+main ()
+{
+sendfile(1, 2, (off_t*)0, sizeof 1);
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+ glibcxx_cv_sendfile=yes
+else
+ glibcxx_cv_sendfile=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+ conftest$ac_exeext conftest.$ac_ext
+fi
+ ;;
+ *)
+ glibcxx_cv_sendfile=no
+ ;;
+ esac
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_sendfile" >&5
+$as_echo "$glibcxx_cv_sendfile" >&6; }
+ if test $glibcxx_cv_sendfile = yes && test $glibcxx_cv_lseek = yes; then
+
+$as_echo "#define _GLIBCXX_USE_SENDFILE 1" >>confdefs.h
+
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for fdopendir" >&5
$as_echo_n "checking for fdopendir... " >&6; }
diff --git a/libstdc++-v3/src/filesystem/ops-common.h b/libstdc++-v3/src/filesystem/ops-common.h
index c95511b5c95..36444388208 100644
--- a/libstdc++-v3/src/filesystem/ops-common.h
+++ b/libstdc++-v3/src/filesystem/ops-common.h
@@ -51,6 +51,7 @@
# include <ext/stdio_filebuf.h>
# ifdef _GLIBCXX_USE_SENDFILE
# include <sys/sendfile.h> // sendfile
+# include <unistd.h> // lseek
# endif
#endif
@@ -358,6 +359,34 @@ _GLIBCXX_BEGIN_NAMESPACE_FILESYSTEM
}
#ifdef NEED_DO_COPY_FILE
+#if defined _GLIBCXX_USE_SENDFILE && ! defined _GLIBCXX_FILESYSTEM_IS_WINDOWS
+ bool
+ copy_file_sendfile(int fd_in, int fd_out, size_t length) noexcept
+ {
+ // a zero-length file is either empty, or not copyable by this syscall
+ // return early to avoid the syscall cost
+ if (length == 0)
+ {
+ errno = EINVAL;
+ return false;
+ }
+ size_t bytes_left = length;
+ off_t offset = 0;
+ ssize_t bytes_copied;
+ do
+ {
+ bytes_copied = ::sendfile(fd_out, fd_in, &offset, bytes_left);
+ bytes_left -= bytes_copied;
+ }
+ while (bytes_left > 0 && bytes_copied > 0);
+ if (bytes_copied < 0)
+ {
+ ::lseek(fd_out, 0, SEEK_SET);
+ return false;
+ }
+ return true;
+ }
+#endif
bool
do_copy_file(const char_type* from, const char_type* to,
std::filesystem::copy_options_existing_file options,
@@ -498,16 +527,22 @@ _GLIBCXX_BEGIN_NAMESPACE_FILESYSTEM
return false;
}
- size_t count = from_st->st_size;
+ bool has_copied = false;
+
#if defined _GLIBCXX_USE_SENDFILE && ! defined _GLIBCXX_FILESYSTEM_IS_WINDOWS
- off_t offset = 0;
- ssize_t n = ::sendfile(out.fd, in.fd, &offset, count);
- if (n < 0 && errno != ENOSYS && errno != EINVAL)
+ if (!has_copied)
+ has_copied = copy_file_sendfile(in.fd, out.fd, from_st->st_size);
+ if (!has_copied)
{
- ec.assign(errno, std::generic_category());
- return false;
+ if (errno != ENOSYS && errno != EINVAL)
+ {
+ ec.assign(errno, std::generic_category());
+ return false;
+ }
}
- if ((size_t)n == count)
+#endif
+
+ if (has_copied)
{
if (!out.close() || !in.close())
{
@@ -517,9 +552,6 @@ _GLIBCXX_BEGIN_NAMESPACE_FILESYSTEM
ec.clear();
return true;
}
- else if (n > 0)
- count -= n;
-#endif // _GLIBCXX_USE_SENDFILE
using std::ios;
__gnu_cxx::stdio_filebuf<char> sbin(in.fd, ios::in|ios::binary);
@@ -530,29 +562,12 @@ _GLIBCXX_BEGIN_NAMESPACE_FILESYSTEM
if (sbout.is_open())
out.fd = -1;
-#ifdef _GLIBCXX_USE_SENDFILE
- if (n != 0)
- {
- if (n < 0)
- n = 0;
-
- const auto p1 = sbin.pubseekoff(n, ios::beg, ios::in);
- const auto p2 = sbout.pubseekoff(n, ios::beg, ios::out);
-
- const std::streampos errpos(std::streamoff(-1));
- if (p1 == errpos || p2 == errpos)
- {
- ec = std::make_error_code(std::errc::io_error);
- return false;
- }
- }
-#endif
-
- if (count && !(std::ostream(&sbout) << &sbin))
+ if (from_st->st_size && !(std::ostream(&sbout) << &sbin))
{
ec = std::make_error_code(std::errc::io_error);
return false;
}
+
if (!sbout.close() || !sbin.close())
{
ec.assign(errno, std::generic_category());
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