Arrange to call AbsorbFsyncRequests every so often while performing a

[postgresql] / src / backend / storage / buffer / bufmgr.c

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 11e83812d0c0712053995fd7347a04e29f7a9912..41ca4c14495f88983f344d2ae29c9a5271dfbcaf 100644 (file)
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.202 2006/01/06 00:04:20 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.203 2006/03/03 00:02:01 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -42,6 +42,7 @@
 
 #include "lib/stringinfo.h"
 #include "miscadmin.h"
+#include "postmaster/bgwriter.h"
 #include "storage/buf_internals.h"
 #include "storage/bufmgr.h"
 #include "storage/bufpage.h"
@@ -61,6 +62,9 @@
 #define LocalBufHdrGetBlock(bufHdr) \
        LocalBufferBlockPointers[-((bufHdr)->buf_id + 2)]
 
+/* interval for calling AbsorbFsyncRequests in BufferSync */
+#define WRITES_PER_ABSORB              1000
+
 
 /* GUC variables */
 bool           zero_damaged_pages = false;
@@ -892,6 +896,7 @@ BufferSync(void)
 {
        int                     buf_id;
        int                     num_to_scan;
+       int                     absorb_counter;
 
        /*
         * Find out where to start the circular scan.
@@ -905,9 +910,23 @@ BufferSync(void)
         * Loop over all buffers.
         */
        num_to_scan = NBuffers;
+       absorb_counter = WRITES_PER_ABSORB;
        while (num_to_scan-- > 0)
        {
-               (void) SyncOneBuffer(buf_id, false);
+               if (SyncOneBuffer(buf_id, false))
+               {
+                       /*
+                        * If in bgwriter, absorb pending fsync requests after each
+                        * WRITES_PER_ABSORB write operations, to prevent overflow of
+                        * the fsync request queue.  If not in bgwriter process, this is
+                        * a no-op.
+                        */
+                       if (--absorb_counter <= 0)
+                       {
+                               AbsorbFsyncRequests();
+                               absorb_counter = WRITES_PER_ABSORB;
+                       }
+               }
                if (++buf_id >= NBuffers)
                        buf_id = 0;
        }