From 6ff02fbc9f4b47456ccb367b21d2b489845620ce Mon Sep 17 00:00:00 2001 From: Nathan Bossart Date: Wed, 11 Aug 2021 22:43:03 +0000 Subject: [PATCH v3 1/1] introduce option for retreiving shmem size --- src/backend/bootstrap/bootstrap.c | 18 +++-- src/backend/main/main.c | 6 +- src/backend/storage/ipc/ipci.c | 142 ++++++++++++++++++++++---------------- src/include/bootstrap/bootstrap.h | 2 +- src/include/storage/ipc.h | 1 + 5 files changed, 102 insertions(+), 67 deletions(-) diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c index 48615c0ebc..c9b2284ad2 100644 --- a/src/backend/bootstrap/bootstrap.c +++ b/src/backend/bootstrap/bootstrap.c @@ -198,9 +198,13 @@ CheckerModeMain(void) * the current configuration, particularly the passed in options pertaining * to shared memory sizing, options work (or at least do not cause an error * up to shared memory creation). + * + * When output_shmem is true, startup is done only far enough to calculate the + * amount of shared memory required for the current configuration. The result + * of this calculation is printed. */ void -BootstrapModeMain(int argc, char *argv[], bool check_only) +BootstrapModeMain(int argc, char *argv[], bool check_only, bool output_shmem) { int i; char *progname = argv[0]; @@ -214,10 +218,11 @@ BootstrapModeMain(int argc, char *argv[], bool check_only) /* Set defaults, to be overridden by explicit options below */ InitializeGUCOptions(); - /* an initial --boot or --check should be present */ + /* an initial --boot, --check, or --output-shmem should be present */ Assert(argc > 1 && (strcmp(argv[1], "--boot") == 0 - || strcmp(argv[1], "--check") == 0)); + || strcmp(argv[1], "--check") == 0 + || strcmp(argv[1], "--output-shmem") == 0)); argv++; argc--; @@ -324,14 +329,17 @@ BootstrapModeMain(int argc, char *argv[], bool check_only) InitializeMaxBackends(); - CreateSharedMemoryAndSemaphores(); + if (output_shmem) + printf("%zu bytes\n", CalculateShmemSize(NULL)); + else + CreateSharedMemoryAndSemaphores(); /* * XXX: It might make sense to move this into its own function at some * point. Right now it seems like it'd cause more code duplication than * it's worth. */ - if (check_only) + if (check_only || output_shmem) { SetProcessingMode(NormalProcessing); CheckerModeMain(); diff --git a/src/backend/main/main.c b/src/backend/main/main.c index 3a2a0d598c..c141ae3d1c 100644 --- a/src/backend/main/main.c +++ b/src/backend/main/main.c @@ -182,9 +182,11 @@ main(int argc, char *argv[]) */ if (argc > 1 && strcmp(argv[1], "--check") == 0) - BootstrapModeMain(argc, argv, true); + BootstrapModeMain(argc, argv, true, false); + else if (argc > 1 && strcmp(argv[1], "--output-shmem") == 0) + BootstrapModeMain(argc, argv, false, true); else if (argc > 1 && strcmp(argv[1], "--boot") == 0) - BootstrapModeMain(argc, argv, false); + BootstrapModeMain(argc, argv, false, false); #ifdef EXEC_BACKEND else if (argc > 1 && strncmp(argv[1], "--fork", 6) == 0) SubPostmasterMain(argc, argv); diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index 3e4ec53a97..b225b1ee70 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -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); /* diff --git a/src/include/bootstrap/bootstrap.h b/src/include/bootstrap/bootstrap.h index 7d3b78e374..8e420574f5 100644 --- a/src/include/bootstrap/bootstrap.h +++ b/src/include/bootstrap/bootstrap.h @@ -32,7 +32,7 @@ extern Form_pg_attribute attrtypes[MAXATTR]; extern int numattr; -extern void BootstrapModeMain(int argc, char *argv[], bool check_only) pg_attribute_noreturn(); +extern void BootstrapModeMain(int argc, char *argv[], bool check_only, bool output_shmem) pg_attribute_noreturn(); extern void closerel(char *name); extern void boot_openrel(char *name); diff --git a/src/include/storage/ipc.h b/src/include/storage/ipc.h index 753a6dd4d7..80e191d407 100644 --- a/src/include/storage/ipc.h +++ b/src/include/storage/ipc.h @@ -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 */ -- 2.16.6