#include "postgres.h"
#include "storage/aio.h"
#include "storage/buf_internals.h"
#include "storage/bufmgr.h"

Include dependency graph for buf_init.c:

Functions
void	BufferManagerShmemInit (void)

Size	BufferManagerShmemSize (void)

Variables
BufferDescPadded *	BufferDescriptors

char *	BufferBlocks

ConditionVariableMinimallyPadded *	BufferIOCVArray

WritebackContext	BackendWritebackContext

CkptSortItem *	CkptBufferIds

Function Documentation

◆ BufferManagerShmemInit()

void BufferManagerShmemInit ( void )

Definition at line 68 of file buf_init.c.

{
    bool        foundBufs,
                foundDescs,
                foundIOCV,
                foundBufCkpt;
 
    /* Align descriptors to a cacheline boundary. */
    BufferDescriptors = (BufferDescPadded *)
        ShmemInitStruct("Buffer Descriptors",
                        NBuffers * sizeof(BufferDescPadded),
                        &foundDescs);
 
    /* Align buffer pool on IO page size boundary. */
    BufferBlocks = (char *)
        TYPEALIGN(PG_IO_ALIGN_SIZE,
                  ShmemInitStruct("Buffer Blocks",
                                  NBuffers * (Size) BLCKSZ + PG_IO_ALIGN_SIZE,
                                  &foundBufs));
 
    /* Align condition variables to cacheline boundary. */
    BufferIOCVArray = (ConditionVariableMinimallyPadded *)
        ShmemInitStruct("Buffer IO Condition Variables",
                        NBuffers * sizeof(ConditionVariableMinimallyPadded),
                        &foundIOCV);
 
    /*
     * The array used to sort to-be-checkpointed buffer ids is located in
     * shared memory, to avoid having to allocate significant amounts of
     * memory at runtime. As that'd be in the middle of a checkpoint, or when
     * the checkpointer is restarted, memory allocation failures would be
     * painful.
     */
    CkptBufferIds = (CkptSortItem *)
        ShmemInitStruct("Checkpoint BufferIds",
                        NBuffers * sizeof(CkptSortItem), &foundBufCkpt);
 
    if (foundDescs || foundBufs || foundIOCV || foundBufCkpt)
    {
        /* should find all of these, or none of them */
        Assert(foundDescs && foundBufs && foundIOCV && foundBufCkpt);
        /* note: this path is only taken in EXEC_BACKEND case */
    }
    else
    {
        int         i;
 
        /*
         * Initialize all the buffer headers.
         */
        for (i = 0; i < NBuffers; i++)
        {
            BufferDesc *buf = GetBufferDescriptor(i);
 
            ClearBufferTag(&buf->tag);
 
            pg_atomic_init_u32(&buf->state, 0);
            buf->wait_backend_pgprocno = INVALID_PROC_NUMBER;
 
            buf->buf_id = i;
 
            pgaio_wref_clear(&buf->io_wref);
 
            /*
             * Initially link all the buffers together as unused. Subsequent
             * management of this list is done by freelist.c.
             */
            buf->freeNext = i + 1;
 
            LWLockInitialize(BufferDescriptorGetContentLock(buf),
                             LWTRANCHE_BUFFER_CONTENT);
 
            ConditionVariableInit(BufferDescriptorGetIOCV(buf));
        }
 
        /* Correct last entry of linked list */
        GetBufferDescriptor(NBuffers - 1)->freeNext = FREENEXT_END_OF_LIST;
    }
 
    /* Init other shared buffer-management stuff */
    StrategyInitialize(!foundDescs);
 
    /* Initialize per-backend file flush context */
    WritebackContextInit(&BackendWritebackContext,
                         &backend_flush_after);
}

References Assert(), backend_flush_after, BackendWritebackContext, buf, BufferBlocks, BufferDescriptorGetContentLock(), BufferDescriptorGetIOCV(), BufferDescriptors, BufferIOCVArray, CkptBufferIds, ClearBufferTag(), ConditionVariableInit(), BufferDesc::freeNext, FREENEXT_END_OF_LIST, GetBufferDescriptor(), i, INVALID_PROC_NUMBER, LWLockInitialize(), LWTRANCHE_BUFFER_CONTENT, NBuffers, pg_atomic_init_u32(), PG_IO_ALIGN_SIZE, pgaio_wref_clear(), ShmemInitStruct(), StrategyInitialize(), TYPEALIGN, and WritebackContextInit().

Referenced by CreateOrAttachShmemStructs().

◆ BufferManagerShmemSize()

Size BufferManagerShmemSize ( void )

Definition at line 162 of file buf_init.c.

{
    Size        size = 0;
 
    /* size of buffer descriptors */
    size = add_size(size, mul_size(NBuffers, sizeof(BufferDescPadded)));
    /* to allow aligning buffer descriptors */
    size = add_size(size, PG_CACHE_LINE_SIZE);
 
    /* size of data pages, plus alignment padding */
    size = add_size(size, PG_IO_ALIGN_SIZE);
    size = add_size(size, mul_size(NBuffers, BLCKSZ));
 
    /* size of stuff controlled by freelist.c */
    size = add_size(size, StrategyShmemSize());
 
    /* size of I/O condition variables */
    size = add_size(size, mul_size(NBuffers,
                                   sizeof(ConditionVariableMinimallyPadded)));
    /* to allow aligning the above */
    size = add_size(size, PG_CACHE_LINE_SIZE);
 
    /* size of checkpoint sort array in bufmgr.c */
    size = add_size(size, mul_size(NBuffers, sizeof(CkptSortItem)));
 
    return size;
}