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Commit0bd305e

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Move the shared memory size calculation to its own function
This change refactors the shared memory size calculation inCreateSharedMemoryAndSemaphores() to its own function. This is intendedfor use in a future change related to the setup of huge pages and sharedmemory with some GUCs, while useful on its own for extensions.Author: Nathan BossartDiscussion:https://postgr.es/m/F2772387-CE0F-46BF-B5F1-CC55516EB885@amazon.com
1 parent5fcb23c commit0bd305e

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2 files changed

+84
-59
lines changed

2 files changed

+84
-59
lines changed

‎src/backend/storage/ipc/ipci.c

Lines changed: 83 additions & 59 deletions
Original file line numberDiff line numberDiff line change
@@ -75,6 +75,87 @@ RequestAddinShmemSpace(Size size)
7575
total_addin_request=add_size(total_addin_request,size);
7676
}
7777

78+
/*
79+
* CalculateShmemSize
80+
*Calculates the amount of shared memory and number of semaphores needed.
81+
*
82+
* If num_semaphores is not NULL, it will be set to the number of semaphores
83+
* required.
84+
*
85+
* Note that this function freezes the additional shared memory request size
86+
* from loadable modules.
87+
*/
88+
Size
89+
CalculateShmemSize(int*num_semaphores)
90+
{
91+
Sizesize;
92+
intnumSemas;
93+
94+
/* Compute number of semaphores we'll need */
95+
numSemas=ProcGlobalSemas();
96+
numSemas+=SpinlockSemas();
97+
98+
/* Return the number of semaphores if requested by the caller */
99+
if (num_semaphores)
100+
*num_semaphores=numSemas;
101+
102+
/*
103+
* Size of the Postgres shared-memory block is estimated via moderately-
104+
* accurate estimates for the big hogs, plus 100K for the stuff that's too
105+
* small to bother with estimating.
106+
*
107+
* We take some care to ensure that the total size request doesn't
108+
* overflow size_t. If this gets through, we don't need to be so careful
109+
* during the actual allocation phase.
110+
*/
111+
size=100000;
112+
size=add_size(size,PGSemaphoreShmemSize(numSemas));
113+
size=add_size(size,SpinlockSemaSize());
114+
size=add_size(size,hash_estimate_size(SHMEM_INDEX_SIZE,
115+
sizeof(ShmemIndexEnt)));
116+
size=add_size(size,dsm_estimate_size());
117+
size=add_size(size,BufferShmemSize());
118+
size=add_size(size,LockShmemSize());
119+
size=add_size(size,PredicateLockShmemSize());
120+
size=add_size(size,ProcGlobalShmemSize());
121+
size=add_size(size,XLOGShmemSize());
122+
size=add_size(size,CLOGShmemSize());
123+
size=add_size(size,CommitTsShmemSize());
124+
size=add_size(size,SUBTRANSShmemSize());
125+
size=add_size(size,TwoPhaseShmemSize());
126+
size=add_size(size,BackgroundWorkerShmemSize());
127+
size=add_size(size,MultiXactShmemSize());
128+
size=add_size(size,LWLockShmemSize());
129+
size=add_size(size,ProcArrayShmemSize());
130+
size=add_size(size,BackendStatusShmemSize());
131+
size=add_size(size,SInvalShmemSize());
132+
size=add_size(size,PMSignalShmemSize());
133+
size=add_size(size,ProcSignalShmemSize());
134+
size=add_size(size,CheckpointerShmemSize());
135+
size=add_size(size,AutoVacuumShmemSize());
136+
size=add_size(size,ReplicationSlotsShmemSize());
137+
size=add_size(size,ReplicationOriginShmemSize());
138+
size=add_size(size,WalSndShmemSize());
139+
size=add_size(size,WalRcvShmemSize());
140+
size=add_size(size,PgArchShmemSize());
141+
size=add_size(size,ApplyLauncherShmemSize());
142+
size=add_size(size,SnapMgrShmemSize());
143+
size=add_size(size,BTreeShmemSize());
144+
size=add_size(size,SyncScanShmemSize());
145+
size=add_size(size,AsyncShmemSize());
146+
#ifdefEXEC_BACKEND
147+
size=add_size(size,ShmemBackendArraySize());
148+
#endif
149+
150+
/* freeze the addin request size and include it */
151+
addin_request_allowed= false;
152+
size=add_size(size,total_addin_request);
153+
154+
/* might as well round it off to a multiple of a typical page size */
155+
size=add_size(size,8192- (size %8192));
156+
157+
returnsize;
158+
}
78159

79160
/*
80161
* CreateSharedMemoryAndSemaphores
@@ -102,65 +183,8 @@ CreateSharedMemoryAndSemaphores(void)
102183
Sizesize;
103184
intnumSemas;
104185

105-
/* Compute number of semaphores we'll need */
106-
numSemas=ProcGlobalSemas();
107-
numSemas+=SpinlockSemas();
108-
109-
/*
110-
* Size of the Postgres shared-memory block is estimated via
111-
* moderately-accurate estimates for the big hogs, plus 100K for the
112-
* stuff that's too small to bother with estimating.
113-
*
114-
* We take some care during this phase to ensure that the total size
115-
* request doesn't overflow size_t. If this gets through, we don't
116-
* need to be so careful during the actual allocation phase.
117-
*/
118-
size=100000;
119-
size=add_size(size,PGSemaphoreShmemSize(numSemas));
120-
size=add_size(size,SpinlockSemaSize());
121-
size=add_size(size,hash_estimate_size(SHMEM_INDEX_SIZE,
122-
sizeof(ShmemIndexEnt)));
123-
size=add_size(size,dsm_estimate_size());
124-
size=add_size(size,BufferShmemSize());
125-
size=add_size(size,LockShmemSize());
126-
size=add_size(size,PredicateLockShmemSize());
127-
size=add_size(size,ProcGlobalShmemSize());
128-
size=add_size(size,XLOGShmemSize());
129-
size=add_size(size,CLOGShmemSize());
130-
size=add_size(size,CommitTsShmemSize());
131-
size=add_size(size,SUBTRANSShmemSize());
132-
size=add_size(size,TwoPhaseShmemSize());
133-
size=add_size(size,BackgroundWorkerShmemSize());
134-
size=add_size(size,MultiXactShmemSize());
135-
size=add_size(size,LWLockShmemSize());
136-
size=add_size(size,ProcArrayShmemSize());
137-
size=add_size(size,BackendStatusShmemSize());
138-
size=add_size(size,SInvalShmemSize());
139-
size=add_size(size,PMSignalShmemSize());
140-
size=add_size(size,ProcSignalShmemSize());
141-
size=add_size(size,CheckpointerShmemSize());
142-
size=add_size(size,AutoVacuumShmemSize());
143-
size=add_size(size,ReplicationSlotsShmemSize());
144-
size=add_size(size,ReplicationOriginShmemSize());
145-
size=add_size(size,WalSndShmemSize());
146-
size=add_size(size,WalRcvShmemSize());
147-
size=add_size(size,PgArchShmemSize());
148-
size=add_size(size,ApplyLauncherShmemSize());
149-
size=add_size(size,SnapMgrShmemSize());
150-
size=add_size(size,BTreeShmemSize());
151-
size=add_size(size,SyncScanShmemSize());
152-
size=add_size(size,AsyncShmemSize());
153-
#ifdefEXEC_BACKEND
154-
size=add_size(size,ShmemBackendArraySize());
155-
#endif
156-
157-
/* freeze the addin request size and include it */
158-
addin_request_allowed= false;
159-
size=add_size(size,total_addin_request);
160-
161-
/* might as well round it off to a multiple of a typical page size */
162-
size=add_size(size,8192- (size %8192));
163-
186+
/* Compute the size of the shared-memory block */
187+
size=CalculateShmemSize(&numSemas);
164188
elog(DEBUG3,"invoking IpcMemoryCreate(size=%zu)",size);
165189

166190
/*

‎src/include/storage/ipc.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -77,6 +77,7 @@ extern void check_on_shmem_exit_lists_are_empty(void);
7777
/* ipci.c */
7878
externPGDLLIMPORTshmem_startup_hook_typeshmem_startup_hook;
7979

80+
externSizeCalculateShmemSize(int*num_semaphores);
8081
externvoidCreateSharedMemoryAndSemaphores(void);
8182

8283
#endif/* IPC_H */

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