Tune BufferGetLSNAtomic() when checksums !enabled

From performance analysis by Heikki Linnakangas

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 1cd0ac806a7b086989a71e21029c7d3314832725..c2ef53f4617ec466d60e1d4033745de33021ebb3 100644 (file)
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -2079,8 +2079,10 @@ BufferGetLSNAtomic(Buffer buffer)
    char                *page = BufferGetPage(buffer);
    XLogRecPtr           lsn;
 
-   /* Local buffers don't need a lock. */
-   if (BufferIsLocal(buffer))
+   /*
+    * If we don't need locking for correctness, fastpath out.
+    */
+   if (!DataChecksumsEnabled() || BufferIsLocal(buffer))
        return PageGetLSN(page);
 
    /* Make sure we've got a real buffer, and that we hold a pin on it. */