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Move the shared memory size calculation to its own function

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This change refactors the shared memory size calculation in
CreateSharedMemoryAndSemaphores() to its own function.  This is intended
for use in a future change related to the setup of huge pages and shared
memory with some GUCs, while useful on its own for extensions.

Author: Nathan Bossart
Discussion: https://postgr.es/m/F2772387-CE0F-46BF-B5F1-CC55516EB885@amazon.com
This commit is contained in:
Michael Paquier 2021-09-06 10:59:20 +09:00
parent 5fcb23c18f
commit 0bd305ee1d
2 changed files with 84 additions and 59 deletions
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142
src/backend/storage/ipc/ipci.c
View File

@ -75,6 +75,87 @@ RequestAddinShmemSpace(Size size)
total_addin_request = add_size(total_addin_request, size);
}
/*
* CalculateShmemSize
* Calculates the amount of shared memory and number of semaphores needed.
*
* If num_semaphores is not NULL, it will be set to the number of semaphores
* required.
*
* Note that this function freezes the additional shared memory request size
* from loadable modules.
*/
Size
CalculateShmemSize(int *num_semaphores)
{
Size size;
int numSemas;
/* Compute number of semaphores we'll need */
numSemas = ProcGlobalSemas();
numSemas += SpinlockSemas();
/* Return the number of semaphores if requested by the caller */
if (num_semaphores)
*num_semaphores = numSemas;
/*
* Size of the Postgres shared-memory block is estimated via moderately-
* accurate estimates for the big hogs, plus 100K for the stuff that's too
* small to bother with estimating.
*
* We take some care to ensure that the total size request doesn't
* overflow size_t. If this gets through, we don't need to be so careful
* during the actual allocation phase.
*/
size = 100000;
size = add_size(size, PGSemaphoreShmemSize(numSemas));
size = add_size(size, SpinlockSemaSize());
size = add_size(size, hash_estimate_size(SHMEM_INDEX_SIZE,
sizeof(ShmemIndexEnt)));
size = add_size(size, dsm_estimate_size());
size = add_size(size, BufferShmemSize());
size = add_size(size, LockShmemSize());
size = add_size(size, PredicateLockShmemSize());
size = add_size(size, ProcGlobalShmemSize());
size = add_size(size, XLOGShmemSize());
size = add_size(size, CLOGShmemSize());
size = add_size(size, CommitTsShmemSize());
size = add_size(size, SUBTRANSShmemSize());
size = add_size(size, TwoPhaseShmemSize());
size = add_size(size, BackgroundWorkerShmemSize());
size = add_size(size, MultiXactShmemSize());
size = add_size(size, LWLockShmemSize());
size = add_size(size, ProcArrayShmemSize());
size = add_size(size, BackendStatusShmemSize());
size = add_size(size, SInvalShmemSize());
size = add_size(size, PMSignalShmemSize());
size = add_size(size, ProcSignalShmemSize());
size = add_size(size, CheckpointerShmemSize());
size = add_size(size, AutoVacuumShmemSize());
size = add_size(size, ReplicationSlotsShmemSize());
size = add_size(size, ReplicationOriginShmemSize());
size = add_size(size, WalSndShmemSize());
size = add_size(size, WalRcvShmemSize());
size = add_size(size, PgArchShmemSize());
size = add_size(size, ApplyLauncherShmemSize());
size = add_size(size, SnapMgrShmemSize());
size = add_size(size, BTreeShmemSize());
size = add_size(size, SyncScanShmemSize());
size = add_size(size, AsyncShmemSize());
#ifdef EXEC_BACKEND
size = add_size(size, ShmemBackendArraySize());
#endif
/* freeze the addin request size and include it */
addin_request_allowed = false;
size = add_size(size, total_addin_request);
/* might as well round it off to a multiple of a typical page size */
size = add_size(size, 8192 - (size % 8192));
return size;
}
/*
* CreateSharedMemoryAndSemaphores
@ -102,65 +183,8 @@ CreateSharedMemoryAndSemaphores(void)
Size size;
int numSemas;
/* Compute number of semaphores we'll need */
numSemas = ProcGlobalSemas();
numSemas += SpinlockSemas();
/*
* Size of the Postgres shared-memory block is estimated via
* moderately-accurate estimates for the big hogs, plus 100K for the
* stuff that's too small to bother with estimating.
*
* We take some care during this phase to ensure that the total size
* request doesn't overflow size_t. If this gets through, we don't
* need to be so careful during the actual allocation phase.
*/
size = 100000;
size = add_size(size, PGSemaphoreShmemSize(numSemas));
size = add_size(size, SpinlockSemaSize());
size = add_size(size, hash_estimate_size(SHMEM_INDEX_SIZE,
sizeof(ShmemIndexEnt)));
size = add_size(size, dsm_estimate_size());
size = add_size(size, BufferShmemSize());
size = add_size(size, LockShmemSize());
size = add_size(size, PredicateLockShmemSize());
size = add_size(size, ProcGlobalShmemSize());
size = add_size(size, XLOGShmemSize());
size = add_size(size, CLOGShmemSize());
size = add_size(size, CommitTsShmemSize());
size = add_size(size, SUBTRANSShmemSize());
size = add_size(size, TwoPhaseShmemSize());
size = add_size(size, BackgroundWorkerShmemSize());
size = add_size(size, MultiXactShmemSize());
size = add_size(size, LWLockShmemSize());
size = add_size(size, ProcArrayShmemSize());
size = add_size(size, BackendStatusShmemSize());
size = add_size(size, SInvalShmemSize());
size = add_size(size, PMSignalShmemSize());
size = add_size(size, ProcSignalShmemSize());
size = add_size(size, CheckpointerShmemSize());
size = add_size(size, AutoVacuumShmemSize());
size = add_size(size, ReplicationSlotsShmemSize());
size = add_size(size, ReplicationOriginShmemSize());
size = add_size(size, WalSndShmemSize());
size = add_size(size, WalRcvShmemSize());
size = add_size(size, PgArchShmemSize());
size = add_size(size, ApplyLauncherShmemSize());
size = add_size(size, SnapMgrShmemSize());
size = add_size(size, BTreeShmemSize());
size = add_size(size, SyncScanShmemSize());
size = add_size(size, AsyncShmemSize());
#ifdef EXEC_BACKEND
size = add_size(size, ShmemBackendArraySize());
#endif
/* freeze the addin request size and include it */
addin_request_allowed = false;
size = add_size(size, total_addin_request);
/* might as well round it off to a multiple of a typical page size */
size = add_size(size, 8192 - (size % 8192));
/* Compute the size of the shared-memory block */
size = CalculateShmemSize(&numSemas);
elog(DEBUG3, "invoking IpcMemoryCreate(size=%zu)", size);
/*

1
src/include/storage/ipc.h
View File

@ -77,6 +77,7 @@ extern void check_on_shmem_exit_lists_are_empty(void);
/* ipci.c */
extern PGDLLIMPORT shmem_startup_hook_type shmem_startup_hook;
extern Size CalculateShmemSize(int *num_semaphores);
extern void CreateSharedMemoryAndSemaphores(void);
#endif /* IPC_H */