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Remove --disable-spinlocks.
A later change will require atomic support, so it wouldn't make sense for a hypothetical new system not to be able to implement spinlocks. Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> (concept, not the patch) Reviewed-by: Andres Freund <andres@anarazel.de> (concept, not the patch) Discussion: https://postgr.es/m/3351991.1697728588%40sss.pgh.pa.us
1 parent 1330843 commit e256266

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20 files changed

+13
-486
lines changed

20 files changed

+13
-486
lines changed

‎configure

Lines changed: 0 additions & 40 deletions
Original file line numberDiff line numberDiff line change
@@ -836,7 +836,6 @@ enable_integer_datetimes
836836
enable_nls
837837
with_pgport
838838
enable_rpath
839-
enable_spinlocks
840839
enable_atomics
841840
enable_debug
842841
enable_profiling
@@ -1529,7 +1528,6 @@ Optional Features:
15291528
enable Native Language Support
15301529
--disable-rpath do not embed shared library search path in
15311530
executables
1532-
--disable-spinlocks do not use spinlocks
15331531
--disable-atomics do not use atomic operations
15341532
--enable-debug build with debugging symbols (-g)
15351533
--enable-profiling build with profiling enabled
@@ -3266,33 +3264,6 @@ fi
32663264

32673265

32683266

3269-
#
3270-
# Spinlocks
3271-
#
3272-
3273-
3274-
# Check whether --enable-spinlocks was given.
3275-
if test "${enable_spinlocks+set}" = set; then :
3276-
enableval=$enable_spinlocks;
3277-
case $enableval in
3278-
yes)
3279-
:
3280-
;;
3281-
no)
3282-
:
3283-
;;
3284-
*)
3285-
as_fn_error $? "no argument expected for --enable-spinlocks option" "$LINENO" 5
3286-
;;
3287-
esac
3288-
3289-
else
3290-
enable_spinlocks=yes
3291-
3292-
fi
3293-
3294-
3295-
32963267
#
32973268
# Atomic operations
32983269
#
@@ -12185,17 +12156,6 @@ fi
1218512156

1218612157
fi
1218712158

12188-
if test "$enable_spinlocks" = yes; then
12189-
12190-
$as_echo "#define HAVE_SPINLOCKS 1" >>confdefs.h
12191-
12192-
else
12193-
{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING:
12194-
*** Not using spinlocks will cause poor performance." >&5
12195-
$as_echo "$as_me: WARNING:
12196-
*** Not using spinlocks will cause poor performance." >&2;}
12197-
fi
12198-
1219912159
if test "$enable_atomics" = yes; then
1220012160

1220112161
$as_echo "#define HAVE_ATOMICS 1" >>confdefs.h

‎configure.ac

Lines changed: 0 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -186,12 +186,6 @@ PGAC_ARG_BOOL(enable, rpath, yes,
186186
[do not embed shared library search path in executables])
187187
AC_SUBST(enable_rpath)
188188

189-
#
190-
# Spinlocks
191-
#
192-
PGAC_ARG_BOOL(enable, spinlocks, yes,
193-
[do not use spinlocks])
194-
195189
#
196190
# Atomic operations
197191
#
@@ -1296,13 +1290,6 @@ failure. It is possible the compiler isn't looking in the proper directory.
12961290
Use --without-zlib to disable zlib support.])])
12971291
fi
12981292

1299-
if test "$enable_spinlocks" = yes; then
1300-
AC_DEFINE(HAVE_SPINLOCKS, 1, [Define to 1 if you have spinlocks.])
1301-
else
1302-
AC_MSG_WARN([
1303-
*** Not using spinlocks will cause poor performance.])
1304-
fi
1305-
13061293
if test "$enable_atomics" = yes; then
13071294
AC_DEFINE(HAVE_ATOMICS, 1, [Define to 1 if you want to use atomics if available.])
13081295
else

‎doc/src/sgml/installation.sgml

Lines changed: 1 addition & 36 deletions
Original file line numberDiff line numberDiff line change
@@ -1258,22 +1258,6 @@ build-postgresql:
12581258
</listitem>
12591259
</varlistentry>
12601260

1261-
<varlistentry id="configure-option-disable-spinlocks">
1262-
<term><option>--disable-spinlocks</option></term>
1263-
<listitem>
1264-
<para>
1265-
Allow the build to succeed even if <productname>PostgreSQL</productname>
1266-
has no CPU spinlock support for the platform. The lack of
1267-
spinlock support will result in very poor performance; therefore,
1268-
this option should only be used if the build aborts and
1269-
informs you that the platform lacks spinlock support. If this
1270-
option is required to build <productname>PostgreSQL</productname> on
1271-
your platform, please report the problem to the
1272-
<productname>PostgreSQL</productname> developers.
1273-
</para>
1274-
</listitem>
1275-
</varlistentry>
1276-
12771261
<varlistentry id="configure-option-disable-atomics">
12781262
<term><option>--disable-atomics</option></term>
12791263
<listitem>
@@ -2690,23 +2674,6 @@ ninja install
26902674
</listitem>
26912675
</varlistentry>
26922676

2693-
<varlistentry id="configure-spinlocks-meson">
2694-
<term><option>-Dspinlocks={ true | false }</option></term>
2695-
<listitem>
2696-
<para>
2697-
This option is set to true by default; setting it to false will
2698-
allow the build to succeed even if <productname>PostgreSQL</productname>
2699-
has no CPU spinlock support for the platform. The lack of
2700-
spinlock support will result in very poor performance; therefore,
2701-
this option should only be changed if the build aborts and
2702-
informs you that the platform lacks spinlock support. If setting this
2703-
option to false is required to build <productname>PostgreSQL</productname> on
2704-
your platform, please report the problem to the
2705-
<productname>PostgreSQL</productname> developers.
2706-
</para>
2707-
</listitem>
2708-
</varlistentry>
2709-
27102677
<varlistentry id="configure-atomics-meson">
27112678
<term><option>-Datomics={ true | false }</option></term>
27122679
<listitem>
@@ -2719,6 +2686,7 @@ ninja install
27192686
</para>
27202687
</listitem>
27212688
</varlistentry>
2689+
27222690
</variablelist>
27232691
</sect3>
27242692

@@ -3393,9 +3361,6 @@ export MANPATH
33933361
these CPU architectures: x86, PowerPC, S/390, SPARC, ARM, MIPS,
33943362
and RISC-V, including
33953363
big-endian, little-endian, 32-bit, and 64-bit variants where applicable.
3396-
It is often
3397-
possible to build on an unsupported CPU type by configuring with
3398-
<option>--disable-spinlocks</option>, but performance will be poor.
33993364
</para>
34003365

34013366
<para>

‎meson.build

Lines changed: 0 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -2089,12 +2089,6 @@ endif
20892089
# Atomics
20902090
###############################################################
20912091

2092-
if not get_option('spinlocks')
2093-
warning('Not using spinlocks will cause poor performance')
2094-
else
2095-
cdata.set('HAVE_SPINLOCKS', 1)
2096-
endif
2097-
20982092
if not get_option('atomics')
20992093
warning('Not using atomics will cause poor performance')
21002094
else

‎src/backend/port/atomics.c

Lines changed: 0 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -57,17 +57,7 @@ pg_atomic_init_flag_impl(volatile pg_atomic_flag *ptr)
5757
StaticAssertDecl(sizeof(ptr->sema) >= sizeof(slock_t),
5858
"size mismatch of atomic_flag vs slock_t");
5959

60-
#ifndef HAVE_SPINLOCKS
61-
62-
/*
63-
* NB: If we're using semaphore based TAS emulation, be careful to use a
64-
* separate set of semaphores. Otherwise we'd get in trouble if an atomic
65-
* var would be manipulated while spinlock is held.
66-
*/
67-
s_init_lock_sema((slock_t *) &ptr->sema, true);
68-
#else
6960
SpinLockInit((slock_t *) &ptr->sema);
70-
#endif
7161

7262
ptr->value = false;
7363
}
@@ -108,15 +98,7 @@ pg_atomic_init_u32_impl(volatile pg_atomic_uint32 *ptr, uint32 val_)
10898
StaticAssertDecl(sizeof(ptr->sema) >= sizeof(slock_t),
10999
"size mismatch of atomic_uint32 vs slock_t");
110100

111-
/*
112-
* If we're using semaphore based atomic flags, be careful about nested
113-
* usage of atomics while a spinlock is held.
114-
*/
115-
#ifndef HAVE_SPINLOCKS
116-
s_init_lock_sema((slock_t *) &ptr->sema, true);
117-
#else
118101
SpinLockInit((slock_t *) &ptr->sema);
119-
#endif
120102
ptr->value = val_;
121103
}
122104

@@ -184,15 +166,7 @@ pg_atomic_init_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 val_)
184166
StaticAssertDecl(sizeof(ptr->sema) >= sizeof(slock_t),
185167
"size mismatch of atomic_uint64 vs slock_t");
186168

187-
/*
188-
* If we're using semaphore based atomic flags, be careful about nested
189-
* usage of atomics while a spinlock is held.
190-
*/
191-
#ifndef HAVE_SPINLOCKS
192-
s_init_lock_sema((slock_t *) &ptr->sema, true);
193-
#else
194169
SpinLockInit((slock_t *) &ptr->sema);
195-
#endif
196170
ptr->value = val_;
197171
}
198172

‎src/backend/port/posix_sema.c

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -217,8 +217,7 @@ PGReserveSemaphores(int maxSemas)
217217

218218
/*
219219
* We must use ShmemAllocUnlocked(), since the spinlock protecting
220-
* ShmemAlloc() won't be ready yet. (This ordering is necessary when we
221-
* are emulating spinlocks with semaphores.)
220+
* ShmemAlloc() won't be ready yet.
222221
*/
223222
sharedSemas = (PGSemaphore)
224223
ShmemAllocUnlocked(PGSemaphoreShmemSize(maxSemas));

‎src/backend/port/sysv_sema.c

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -325,8 +325,7 @@ PGReserveSemaphores(int maxSemas)
325325

326326
/*
327327
* We must use ShmemAllocUnlocked(), since the spinlock protecting
328-
* ShmemAlloc() won't be ready yet. (This ordering is necessary when we
329-
* are emulating spinlocks with semaphores.)
328+
* ShmemAlloc() won't be ready yet.
330329
*/
331330
sharedSemas = (PGSemaphore)
332331
ShmemAllocUnlocked(PGSemaphoreShmemSize(maxSemas));

‎src/backend/postmaster/launch_backend.c

Lines changed: 0 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -108,9 +108,7 @@ typedef struct
108108
#ifdef USE_INJECTION_POINTS
109109
struct InjectionPointsCtl *ActiveInjectionPoints;
110110
#endif
111-
#ifndef HAVE_SPINLOCKS
112111
PGSemaphore *SpinlockSemaArray;
113-
#endif
114112
int NamedLWLockTrancheRequests;
115113
NamedLWLockTranche *NamedLWLockTrancheArray;
116114
LWLockPadded *MainLWLockArray;
@@ -724,9 +722,6 @@ save_backend_variables(BackendParameters *param, ClientSocket *client_sock,
724722
param->ActiveInjectionPoints = ActiveInjectionPoints;
725723
#endif
726724

727-
#ifndef HAVE_SPINLOCKS
728-
param->SpinlockSemaArray = SpinlockSemaArray;
729-
#endif
730725
param->NamedLWLockTrancheRequests = NamedLWLockTrancheRequests;
731726
param->NamedLWLockTrancheArray = NamedLWLockTrancheArray;
732727
param->MainLWLockArray = MainLWLockArray;
@@ -986,9 +981,6 @@ restore_backend_variables(BackendParameters *param)
986981
ActiveInjectionPoints = param->ActiveInjectionPoints;
987982
#endif
988983

989-
#ifndef HAVE_SPINLOCKS
990-
SpinlockSemaArray = param->SpinlockSemaArray;
991-
#endif
992984
NamedLWLockTrancheRequests = param->NamedLWLockTrancheRequests;
993985
NamedLWLockTrancheArray = param->NamedLWLockTrancheArray;
994986
MainLWLockArray = param->MainLWLockArray;

‎src/backend/storage/ipc/ipci.c

Lines changed: 0 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -94,7 +94,6 @@ CalculateShmemSize(int *num_semaphores)
9494

9595
/* Compute number of semaphores we'll need */
9696
numSemas = ProcGlobalSemas();
97-
numSemas += SpinlockSemas();
9897

9998
/* Return the number of semaphores if requested by the caller */
10099
if (num_semaphores)
@@ -111,7 +110,6 @@ CalculateShmemSize(int *num_semaphores)
111110
*/
112111
size = 100000;
113112
size = add_size(size, PGSemaphoreShmemSize(numSemas));
114-
size = add_size(size, SpinlockSemaSize());
115113
size = add_size(size, hash_estimate_size(SHMEM_INDEX_SIZE,
116114
sizeof(ShmemIndexEnt)));
117115
size = add_size(size, dsm_estimate_size());
@@ -225,14 +223,6 @@ CreateSharedMemoryAndSemaphores(void)
225223
*/
226224
PGReserveSemaphores(numSemas);
227225

228-
/*
229-
* If spinlocks are disabled, initialize emulation layer (which depends on
230-
* semaphores, so the order is important here).
231-
*/
232-
#ifndef HAVE_SPINLOCKS
233-
SpinlockSemaInit();
234-
#endif
235-
236226
/*
237227
* Set up shared memory allocation mechanism
238228
*/

‎src/backend/storage/lmgr/Makefile

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -21,7 +21,6 @@ OBJS = \
2121
predicate.o \
2222
proc.o \
2323
s_lock.o \
24-
spin.o
2524

2625
include $(top_srcdir)/src/backend/common.mk
2726

‎src/backend/storage/lmgr/meson.build

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,5 +9,4 @@ backend_sources += files(
99
'predicate.c',
1010
'proc.c',
1111
's_lock.c',
12-
'spin.c',
1312
)

‎src/backend/storage/lmgr/s_lock.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
11
/*-------------------------------------------------------------------------
22
*
33
* s_lock.c
4-
* Hardware-dependent implementation of spinlocks.
4+
* Implementation of spinlocks.
55
*
66
* When waiting for a contended spinlock we loop tightly for awhile, then
77
* delay using pg_usleep() and try again. Preferably, "awhile" should be a

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