bufmgr: Pass io_object and io_context through to PinBufferForBlock()

PinBufferForBlock() is always_inline and called in a loop in
StartReadBuffersImpl(). Previously it computed io_context and io_object
internally, which required calling IOContextForStrategy() -- a non-inline
function the compiler cannot prove is side-effect-free. This could potential
cause unneeded redundant function calls.

Compute io_context and io_object in the callers instead, allowing
StartReadBuffersImpl() to do so once before entering the loop.

Author: Melanie Plageman <melanieplageman@gmail.com>
Suggested-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/zljergweqti7x67lg5ije2rzjusie37nslsnkjkkby4laqqbfw@3p3zu522yykv

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 10afae1990ba78b9c273766182082c8aa0188a23..ab9c2a4b9041d4663709b8bb1ddc030a43452752 100644 (file)
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1223,11 +1223,11 @@ PinBufferForBlock(Relation rel,
                                  ForkNumber forkNum,
                                  BlockNumber blockNum,
                                  BufferAccessStrategy strategy,
+                                 IOObject io_object,
+                                 IOContext io_context,
                                  bool *foundPtr)
 {
        BufferDesc *bufHdr;
-       IOContext       io_context;
-       IOObject        io_object;
 
        Assert(blockNum != P_NEW);
 
@@ -1236,17 +1236,6 @@ PinBufferForBlock(Relation rel,
                        persistence == RELPERSISTENCE_PERMANENT ||
                        persistence == RELPERSISTENCE_UNLOGGED));
 
-       if (persistence == RELPERSISTENCE_TEMP)
-       {
-               io_context = IOCONTEXT_NORMAL;
-               io_object = IOOBJECT_TEMP_RELATION;
-       }
-       else
-       {
-               io_context = IOContextForStrategy(strategy);
-               io_object = IOOBJECT_RELATION;
-       }
-
        TRACE_POSTGRESQL_BUFFER_READ_START(forkNum, blockNum,
                                                                           smgr->smgr_rlocator.locator.spcOid,
                                                                           smgr->smgr_rlocator.locator.dbOid,
@@ -1339,9 +1328,23 @@ ReadBuffer_common(Relation rel, SMgrRelation smgr, char smgr_persistence,
                                 mode == RBM_ZERO_AND_LOCK))
        {
                bool            found;
+               IOContext       io_context;
+               IOObject        io_object;
+
+               if (persistence == RELPERSISTENCE_TEMP)
+               {
+                       io_context = IOCONTEXT_NORMAL;
+                       io_object = IOOBJECT_TEMP_RELATION;
+               }
+               else
+               {
+                       io_context = IOContextForStrategy(strategy);
+                       io_object = IOOBJECT_RELATION;
+               }
 
                buffer = PinBufferForBlock(rel, smgr, persistence,
-                                                                  forkNum, blockNum, strategy, &found);
+                                                                  forkNum, blockNum, strategy,
+                                                                  io_object, io_context, &found);
                ZeroAndLockBuffer(buffer, mode, found);
                return buffer;
        }
@@ -1379,11 +1382,24 @@ StartReadBuffersImpl(ReadBuffersOperation *operation,
        int                     actual_nblocks = *nblocks;
        int                     maxcombine = 0;
        bool            did_start_io;
+       IOContext       io_context;
+       IOObject        io_object;
 
        Assert(*nblocks == 1 || allow_forwarding);
        Assert(*nblocks > 0);
        Assert(*nblocks <= MAX_IO_COMBINE_LIMIT);
 
+       if (operation->persistence == RELPERSISTENCE_TEMP)
+       {
+               io_context = IOCONTEXT_NORMAL;
+               io_object = IOOBJECT_TEMP_RELATION;
+       }
+       else
+       {
+               io_context = IOContextForStrategy(operation->strategy);
+               io_object = IOOBJECT_RELATION;
+       }
+
        for (int i = 0; i < actual_nblocks; ++i)
        {
                bool            found;
@@ -1432,6 +1448,7 @@ StartReadBuffersImpl(ReadBuffersOperation *operation,
                                                                                   operation->forknum,
                                                                                   blockNum + i,
                                                                                   operation->strategy,
+                                                                                  io_object, io_context,
                                                                                   &found);
                }