Track SLRU page hits in SimpleLruReadPage_ReadOnly

SLRU page hits were tracked only in SimpleLruReadPage, but that's not
enough because we may hit the page in SimpleLruReadPage_ReadOnly in
which case we don't call SimpleLruReadPage at all.

Reported-by: Kuntal Ghosh
Discussion: https://postgr.es/m/20200119143707.gyinppnigokesjok@development

diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c
index de3c94105d1d0817decf11514a0b47da842ae2be..b2316af7794b325cee89de3d4e356e5f7ab68649 100644 (file)
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -491,6 +491,10 @@ SimpleLruReadPage_ReadOnly(SlruCtl ctl, int pageno, TransactionId xid)
                {
                        /* See comments for SlruRecentlyUsed macro */
                        SlruRecentlyUsed(shared, slotno);
+
+                       /* update the stats counter of pages found in the SLRU */
+                       pgstat_count_slru_page_hit(ctl);
+
                        return slotno;
                }
        }