diff options
Diffstat (limited to 'src/backend/storage/buffer/bufmgr.c')
| -rw-r--r-- | src/backend/storage/buffer/bufmgr.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index b8680cc8fd4..a19595865af 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -1259,6 +1259,7 @@ StartReadBuffersImpl(ReadBuffersOperation *operation, { int actual_nblocks = *nblocks; int io_buffers_len = 0; + int maxcombine = 0; Assert(*nblocks > 0); Assert(*nblocks <= MAX_IO_COMBINE_LIMIT); @@ -1290,6 +1291,23 @@ StartReadBuffersImpl(ReadBuffersOperation *operation, { /* Extend the readable range to cover this block. */ io_buffers_len++; + + /* + * Check how many blocks we can cover with the same IO. The smgr + * implementation might e.g. be limited due to a segment boundary. + */ + if (i == 0 && actual_nblocks > 1) + { + maxcombine = smgrmaxcombine(operation->smgr, + operation->forknum, + blockNum); + if (unlikely(maxcombine < actual_nblocks)) + { + elog(DEBUG2, "limiting nblocks at %u from %u to %u", + blockNum, actual_nblocks, maxcombine); + actual_nblocks = maxcombine; + } + } } } *nblocks = actual_nblocks; |