diff options
| -rw-r--r-- | src/backend/storage/buffer/localbuf.c | 57 |
1 files changed, 51 insertions, 6 deletions
diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c index 38fec03419c..b6f6d89adfa 100644 --- a/src/backend/storage/buffer/localbuf.c +++ b/src/backend/storage/buffer/localbuf.c @@ -9,7 +9,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/buffer/localbuf.c,v 1.70.2.2 2005/11/22 18:23:18 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/storage/buffer/localbuf.c,v 1.70.2.3 2006/12/27 22:32:03 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -48,6 +48,7 @@ static HTAB *LocalBufHash = NULL; static void InitLocalBuffers(void); +static Block GetLocalBufferStorage(void); /* @@ -167,12 +168,8 @@ LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr) */ if (LocalBufHdrGetBlock(bufHdr) == NULL) { - char *data; - - data = (char *) MemoryContextAlloc(TopMemoryContext, BLCKSZ); - /* Set pointer for use by BufferGetBlock() macro */ - LocalBufHdrGetBlock(bufHdr) = (Block) data; + LocalBufHdrGetBlock(bufHdr) = GetLocalBufferStorage(); } /* @@ -344,6 +341,54 @@ InitLocalBuffers(void) } /* + * GetLocalBufferStorage - allocate memory for a local buffer + * + * The idea of this function is to aggregate our requests for storage + * so that the memory manager doesn't see a whole lot of relatively small + * requests. Since we'll never give back a local buffer once it's created + * within a particular process, no point in burdening memmgr with separately + * managed chunks. + */ +static Block +GetLocalBufferStorage(void) +{ + static char *cur_block = NULL; + static int next_buf_in_block = 0; + static int num_bufs_in_block = 0; + static int total_bufs_allocated = 0; + + char *this_buf; + + Assert(total_bufs_allocated < NLocBuffer); + + if (next_buf_in_block >= num_bufs_in_block) + { + /* Need to make a new request to memmgr */ + int num_bufs; + + /* Start with a 16-buffer request; subsequent ones double each time */ + num_bufs = Max(num_bufs_in_block * 2, 16); + /* But not more than what we need for all remaining local bufs */ + num_bufs = Min(num_bufs, NLocBuffer - total_bufs_allocated); + /* And don't overflow MaxAllocSize, either */ + num_bufs = Min(num_bufs, MaxAllocSize / BLCKSZ); + + /* Allocate space from TopMemoryContext so it never goes away */ + cur_block = (char *) MemoryContextAlloc(TopMemoryContext, + num_bufs * BLCKSZ); + next_buf_in_block = 0; + num_bufs_in_block = num_bufs; + } + + /* Allocate next buffer in current memory block */ + this_buf = cur_block + next_buf_in_block * BLCKSZ; + next_buf_in_block++; + total_bufs_allocated++; + + return (Block) this_buf; +} + +/* * AtEOXact_LocalBuffers - clean up at end of transaction. * * This is just like AtEOXact_Buffers, but for local buffers. |