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Add a basic atomic ops API abstracting away platform/architecture details.

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Several upcoming performance/scalability improvements require atomic
operations. This new API avoids the need to splatter compiler and
architecture dependent code over all the locations employing atomic
ops.

For several of the potential usages it'd be problematic to maintain
both, a atomics using implementation and one using spinlocks or
similar. In all likelihood one of the implementations would not get
tested regularly under concurrency. To avoid that scenario the new API
provides a automatic fallback of atomic operations to spinlocks. All
properties of atomic operations are maintained. This fallback -
obviously - isn't as fast as just using atomic ops, but it's not bad
either. For one of the future users the atomics ontop spinlocks
implementation was actually slightly faster than the old purely
spinlock using implementation. That's important because it reduces the
fear of regressing older platforms when improving the scalability for
new ones.

The API, loosely modeled after the C11 atomics support, currently
provides 'atomic flags' and 32 bit unsigned integers. If the platform
efficiently supports atomic 64 bit unsigned integers those are also
provided.

To implement atomics support for a platform/architecture/compiler for
a type of atomics 32bit compare and exchange needs to be
implemented. If available and more efficient native support for flags,
32 bit atomic addition, and corresponding 64 bit operations may also
be provided. Additional useful atomic operations are implemented
generically ontop of these.

The implementation for various versions of gcc, msvc and sun studio have
been tested. Additional existing stub implementations for
* Intel icc
* HUPX acc
* IBM xlc
are included but have never been tested. These will likely require
fixes based on buildfarm and user feedback.

As atomic operations also require barriers for some operations the
existing barrier support has been moved into the atomics code.

Author: Andres Freund with contributions from Oskari Saarenmaa
Reviewed-By: Amit Kapila, Robert Haas, Heikki Linnakangas and Álvaro Herrera
Discussion: CA+TgmoYBW+ux5-8Ja=Mcyuy8=VXAnVRHp3Kess6Pn3DMXAPAEA@mail.gmail.com,
    20131015123303.GH5300@awork2.anarazel.de,
    20131028205522.GI20248@awork2.anarazel.de
This commit is contained in:
Andres Freund
2014-09-25 23:49:05 +02:00
parent 9111d46351
commit b64d92f1a5
31 changed files with 2816 additions and 208 deletions
Download Patch File Download Diff File Expand all files Collapse all files

274
configure vendored
View File

@ -802,6 +802,7 @@ enable_nls
with_pgport
enable_rpath
enable_spinlocks
enable_atomics
enable_debug
enable_profiling
enable_coverage
@ -1470,6 +1471,7 @@ Optional Features:
--disable-rpath do not embed shared library search path in
executables
--disable-spinlocks do not use spinlocks
--disable-atomics do not use atomic operations
--enable-debug build with debugging symbols (-g)
--enable-profiling build with profiling enabled
--enable-coverage build with coverage testing instrumentation
@ -3145,6 +3147,33 @@ fi
#
# Atomic operations
#
# Check whether --enable-atomics was given.
if test "${enable_atomics+set}" = set; then :
enableval=$enable_atomics;
case $enableval in
yes)
:
;;
no)
:
;;
*)
as_fn_error $? "no argument expected for --enable-atomics option" "$LINENO" 5
;;
esac
else
enable_atomics=yes
fi
#
# --enable-debug adds -g to compiler flags
#
@ -8349,6 +8378,17 @@ $as_echo "$as_me: WARNING:
*** Not using spinlocks will cause poor performance." >&2;}
fi
if test "$enable_atomics" = yes; then
$as_echo "#define HAVE_ATOMICS 1" >>confdefs.h
else
{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING:
*** Not using atomic operations will cause poor performance." >&5
$as_echo "$as_me: WARNING:
*** Not using atomic operations will cause poor performance." >&2;}
fi
if test "$with_gssapi" = yes ; then
if test "$PORTNAME" != "win32"; then
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing gss_init_sec_context" >&5
@ -9123,7 +9163,7 @@ fi
done
for ac_header in crypt.h dld.h fp_class.h getopt.h ieeefp.h ifaddrs.h langinfo.h poll.h pwd.h sys/ioctl.h sys/ipc.h sys/poll.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/socket.h sys/sockio.h sys/tas.h sys/time.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h
for ac_header in atomic.h crypt.h dld.h fp_class.h getopt.h ieeefp.h ifaddrs.h langinfo.h poll.h pwd.h sys/ioctl.h sys/ipc.h sys/poll.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/socket.h sys/sockio.h sys/tas.h sys/time.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h
do :
as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
@ -12154,40 +12194,6 @@ fi
done
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for builtin locking functions" >&5
$as_echo_n "checking for builtin locking functions... " >&6; }
if ${pgac_cv_gcc_int_atomics+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
int lock = 0;
__sync_lock_test_and_set(&lock, 1);
__sync_lock_release(&lock);
;
return 0;
}
_ACEOF
if ac_fn_c_try_link "$LINENO"; then :
pgac_cv_gcc_int_atomics="yes"
else
pgac_cv_gcc_int_atomics="no"
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_gcc_int_atomics" >&5
$as_echo "$pgac_cv_gcc_int_atomics" >&6; }
if test x"$pgac_cv_gcc_int_atomics" = x"yes"; then
$as_echo "#define HAVE_GCC_INT_ATOMICS 1" >>confdefs.h
fi
# Lastly, restore full LIBS list and check for readline/libedit symbols
LIBS="$LIBS_including_readline"
@ -13711,6 +13717,204 @@ _ACEOF
fi
# Check for various atomic operations now that we have checked how to declare
# 64bit integers.
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for builtin __sync char locking functions" >&5
$as_echo_n "checking for builtin __sync char locking functions... " >&6; }
if ${pgac_cv_gcc_sync_char_tas+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
char lock = 0;
__sync_lock_test_and_set(&lock, 1);
__sync_lock_release(&lock);
;
return 0;
}
_ACEOF
if ac_fn_c_try_link "$LINENO"; then :
pgac_cv_gcc_sync_char_tas="yes"
else
pgac_cv_gcc_sync_char_tas="no"
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_gcc_sync_char_tas" >&5
$as_echo "$pgac_cv_gcc_sync_char_tas" >&6; }
if test x"$pgac_cv_gcc_sync_char_tas" = x"yes"; then
$as_echo "#define HAVE_GCC__SYNC_CHAR_TAS 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for builtin __sync int32 locking functions" >&5
$as_echo_n "checking for builtin __sync int32 locking functions... " >&6; }
if ${pgac_cv_gcc_sync_int32_tas+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
int lock = 0;
__sync_lock_test_and_set(&lock, 1);
__sync_lock_release(&lock);
;
return 0;
}
_ACEOF
if ac_fn_c_try_link "$LINENO"; then :
pgac_cv_gcc_sync_int32_tas="yes"
else
pgac_cv_gcc_sync_int32_tas="no"
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_gcc_sync_int32_tas" >&5
$as_echo "$pgac_cv_gcc_sync_int32_tas" >&6; }
if test x"$pgac_cv_gcc_sync_int32_tas" = x"yes"; then
$as_echo "#define HAVE_GCC__SYNC_INT32_TAS 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for builtin __sync int32 atomic operations" >&5
$as_echo_n "checking for builtin __sync int32 atomic operations... " >&6; }
if ${pgac_cv_gcc_sync_int32_cas+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
int val = 0;
__sync_val_compare_and_swap(&val, 0, 37);
;
return 0;
}
_ACEOF
if ac_fn_c_try_link "$LINENO"; then :
pgac_cv_gcc_sync_int32_cas="yes"
else
pgac_cv_gcc_sync_int32_cas="no"
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_gcc_sync_int32_cas" >&5
$as_echo "$pgac_cv_gcc_sync_int32_cas" >&6; }
if test x"$pgac_cv_gcc_sync_int32_cas" = x"yes"; then
$as_echo "#define HAVE_GCC__SYNC_INT32_CAS 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for builtin __sync int64 atomic operations" >&5
$as_echo_n "checking for builtin __sync int64 atomic operations... " >&6; }
if ${pgac_cv_gcc_sync_int64_cas+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
PG_INT64_TYPE lock = 0;
__sync_val_compare_and_swap(&lock, 0, (PG_INT64_TYPE) 37);
;
return 0;
}
_ACEOF
if ac_fn_c_try_link "$LINENO"; then :
pgac_cv_gcc_sync_int64_cas="yes"
else
pgac_cv_gcc_sync_int64_cas="no"
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_gcc_sync_int64_cas" >&5
$as_echo "$pgac_cv_gcc_sync_int64_cas" >&6; }
if test x"$pgac_cv_gcc_sync_int64_cas" = x"yes"; then
$as_echo "#define HAVE_GCC__SYNC_INT64_CAS 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for builtin __atomic int32 atomic operations" >&5
$as_echo_n "checking for builtin __atomic int32 atomic operations... " >&6; }
if ${pgac_cv_gcc_atomic_int32_cas+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
int val = 0;
int expect = 0;
__atomic_compare_exchange_n(&val, &expect, 37, 0, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED);
;
return 0;
}
_ACEOF
if ac_fn_c_try_link "$LINENO"; then :
pgac_cv_gcc_atomic_int32_cas="yes"
else
pgac_cv_gcc_atomic_int32_cas="no"
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_gcc_atomic_int32_cas" >&5
$as_echo "$pgac_cv_gcc_atomic_int32_cas" >&6; }
if test x"$pgac_cv_gcc_atomic_int32_cas" = x"yes"; then
$as_echo "#define HAVE_GCC__ATOMIC_INT32_CAS 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for builtin __atomic int64 atomic operations" >&5
$as_echo_n "checking for builtin __atomic int64 atomic operations... " >&6; }
if ${pgac_cv_gcc_atomic_int64_cas+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
PG_INT64_TYPE val = 0;
PG_INT64_TYPE expect = 0;
__atomic_compare_exchange_n(&val, &expect, 37, 0, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED);
;
return 0;
}
_ACEOF
if ac_fn_c_try_link "$LINENO"; then :
pgac_cv_gcc_atomic_int64_cas="yes"
else
pgac_cv_gcc_atomic_int64_cas="no"
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_gcc_atomic_int64_cas" >&5
$as_echo "$pgac_cv_gcc_atomic_int64_cas" >&6; }
if test x"$pgac_cv_gcc_atomic_int64_cas" = x"yes"; then
$as_echo "#define HAVE_GCC__ATOMIC_INT64_CAS 1" >>confdefs.h
fi
if test "$PORTNAME" != "win32"
then