diff options
| -rw-r--r-- | src/backend/executor/nodeBitmapHeapscan.c | 18 | ||||
| -rw-r--r-- | src/backend/storage/buffer/bufmgr.c | 74 | ||||
| -rw-r--r-- | src/backend/utils/misc/guc.c | 29 | ||||
| -rw-r--r-- | src/include/storage/bufmgr.h | 6 |
4 files changed, 14 insertions, 113 deletions
diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c index ae8a11da304..726d3a2d9a4 100644 --- a/src/backend/executor/nodeBitmapHeapscan.c +++ b/src/backend/executor/nodeBitmapHeapscan.c @@ -707,7 +707,6 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags) { BitmapHeapScanState *scanstate; Relation currentRelation; - int io_concurrency; /* check for unsupported flags */ Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK))); @@ -737,8 +736,6 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags) scanstate->prefetch_iterator = NULL; scanstate->prefetch_pages = 0; scanstate->prefetch_target = 0; - /* may be updated below */ - scanstate->prefetch_maximum = target_prefetch_pages; scanstate->pscan_len = 0; scanstate->initialized = false; scanstate->shared_tbmiterator = NULL; @@ -794,20 +791,11 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags) ExecInitQual(node->bitmapqualorig, (PlanState *) scanstate); /* - * Determine the maximum for prefetch_target. If the tablespace has a - * specific IO concurrency set, use that to compute the corresponding - * maximum value; otherwise, we already initialized to the value computed - * by the GUC machinery. + * Maximum number of prefetches for the tablespace if configured, otherwise + * the current value of the effective_io_concurrency GUC. */ - io_concurrency = + scanstate->prefetch_maximum = get_tablespace_io_concurrency(currentRelation->rd_rel->reltablespace); - if (io_concurrency != effective_io_concurrency) - { - double maximum; - - if (ComputeIoConcurrency(io_concurrency, &maximum)) - scanstate->prefetch_maximum = rint(maximum); - } scanstate->ss.ss_currentRelation = currentRelation; diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 58800542454..7a7748b6955 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -110,6 +110,13 @@ bool zero_damaged_pages = false; int bgwriter_lru_maxpages = 100; double bgwriter_lru_multiplier = 2.0; bool track_io_timing = false; + +/* + * How many buffers PrefetchBuffer callers should try to stay ahead of their + * ReadBuffer calls by. Zero means "never prefetch". This value is only used + * for buffers not belonging to tablespaces that have their + * effective_io_concurrency parameter set. + */ int effective_io_concurrency = 0; /* @@ -120,15 +127,6 @@ int checkpoint_flush_after = 0; int bgwriter_flush_after = 0; int backend_flush_after = 0; -/* - * How many buffers PrefetchBuffer callers should try to stay ahead of their - * ReadBuffer calls by. This is maintained by the assign hook for - * effective_io_concurrency. Zero means "never prefetch". This value is - * only used for buffers not belonging to tablespaces that have their - * effective_io_concurrency parameter set. - */ -int target_prefetch_pages = 0; - /* local state for StartBufferIO and related functions */ static BufferDesc *InProgressBuf = NULL; static bool IsForInput; @@ -462,64 +460,6 @@ static int ts_ckpt_progress_comparator(Datum a, Datum b, void *arg); /* - * ComputeIoConcurrency -- get the number of pages to prefetch for a given - * number of spindles. - */ -bool -ComputeIoConcurrency(int io_concurrency, double *target) -{ - double new_prefetch_pages = 0.0; - int i; - - /* - * Make sure the io_concurrency value is within valid range; it may have - * been forced with a manual pg_tablespace update. - */ - io_concurrency = Min(Max(io_concurrency, 0), MAX_IO_CONCURRENCY); - - /*---------- - * The user-visible GUC parameter is the number of drives (spindles), - * which we need to translate to a number-of-pages-to-prefetch target. - * The target value is stashed in *extra and then assigned to the actual - * variable by assign_effective_io_concurrency. - * - * The expected number of prefetch pages needed to keep N drives busy is: - * - * drives | I/O requests - * -------+---------------- - * 1 | 1 - * 2 | 2/1 + 2/2 = 3 - * 3 | 3/1 + 3/2 + 3/3 = 5 1/2 - * 4 | 4/1 + 4/2 + 4/3 + 4/4 = 8 1/3 - * n | n * H(n) - * - * This is called the "coupon collector problem" and H(n) is called the - * harmonic series. This could be approximated by n * ln(n), but for - * reasonable numbers of drives we might as well just compute the series. - * - * Alternatively we could set the target to the number of pages necessary - * so that the expected number of active spindles is some arbitrary - * percentage of the total. This sounds the same but is actually slightly - * different. The result ends up being ln(1-P)/ln((n-1)/n) where P is - * that desired fraction. - * - * Experimental results show that both of these formulas aren't aggressive - * enough, but we don't really have any better proposals. - * - * Note that if io_concurrency = 0 (disabled), we must set target = 0. - *---------- - */ - - for (i = 1; i <= io_concurrency; i++) - new_prefetch_pages += (double) io_concurrency / (double) i; - - *target = new_prefetch_pages; - - /* This range check shouldn't fail, but let's be paranoid */ - return (new_prefetch_pages >= 0.0 && new_prefetch_pages < (double) INT_MAX); -} - -/* * PrefetchBuffer -- initiate asynchronous read of a block of a relation * * This is named by analogy to ReadBuffer but doesn't actually allocate a diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 4c6d6486623..326e773b25f 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -196,7 +196,6 @@ static bool check_autovacuum_max_workers(int *newval, void **extra, GucSource so static bool check_max_wal_senders(int *newval, void **extra, GucSource source); static bool check_autovacuum_work_mem(int *newval, void **extra, GucSource source); static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source); -static void assign_effective_io_concurrency(int newval, void *extra); static void assign_pgstat_temp_directory(const char *newval, void *extra); static bool check_application_name(char **newval, void **extra, GucSource source); static void assign_application_name(const char *newval, void *extra); @@ -2882,7 +2881,7 @@ static struct config_int ConfigureNamesInt[] = 0, #endif 0, MAX_IO_CONCURRENCY, - check_effective_io_concurrency, assign_effective_io_concurrency, NULL + check_effective_io_concurrency, NULL, NULL }, { @@ -11457,36 +11456,14 @@ check_max_worker_processes(int *newval, void **extra, GucSource source) static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source) { -#ifdef USE_PREFETCH - double new_prefetch_pages; - - if (ComputeIoConcurrency(*newval, &new_prefetch_pages)) - { - int *myextra = (int *) guc_malloc(ERROR, sizeof(int)); - - *myextra = (int) rint(new_prefetch_pages); - *extra = (void *) myextra; - - return true; - } - else - return false; -#else +#ifndef USE_PREFETCH if (*newval != 0) { GUC_check_errdetail("effective_io_concurrency must be set to 0 on platforms that lack posix_fadvise()."); return false; } - return true; -#endif /* USE_PREFETCH */ -} - -static void -assign_effective_io_concurrency(int newval, void *extra) -{ -#ifdef USE_PREFETCH - target_prefetch_pages = *((int *) extra); #endif /* USE_PREFETCH */ + return true; } static void diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h index 73c7e9ba386..2bf5afdade6 100644 --- a/src/include/storage/bufmgr.h +++ b/src/include/storage/bufmgr.h @@ -57,7 +57,7 @@ extern bool zero_damaged_pages; extern int bgwriter_lru_maxpages; extern double bgwriter_lru_multiplier; extern bool track_io_timing; -extern int target_prefetch_pages; +extern int effective_io_concurrency; extern int checkpoint_flush_after; extern int backend_flush_after; @@ -66,9 +66,6 @@ extern int bgwriter_flush_after; /* in buf_init.c */ extern PGDLLIMPORT char *BufferBlocks; -/* in guc.c */ -extern int effective_io_concurrency; - /* in localbuf.c */ extern PGDLLIMPORT int NLocBuffer; extern PGDLLIMPORT Block *LocalBufferBlockPointers; @@ -161,7 +158,6 @@ extern PGDLLIMPORT int32 *LocalRefCount; /* * prototypes for functions in bufmgr.c */ -extern bool ComputeIoConcurrency(int io_concurrency, double *target); extern void PrefetchBuffer(Relation reln, ForkNumber forkNum, BlockNumber blockNum); extern Buffer ReadBuffer(Relation reln, BlockNumber blockNum); |