Repair out-of-date information in src/backend/storage/buffer/README.

In commit d526575f893c1a4e05ebd307e80203536b213a6d, we changed things so
that buffer usage counts are incremented when the buffer is pinned, rather
than when it is unpinned, but the README file didn't get the memo.

Report by Amit Kapila.
This commit is contained in:
Robert Haas 2012-05-22 09:30:59 -04:00
parent b94ce6e807
commit 219c024c64

View File

@ -169,8 +169,8 @@ need to take system-wide locks during common operations. It works like
this:
Each buffer header contains a usage counter, which is incremented (up to a
small limit value) whenever the buffer is unpinned. (This requires only the
buffer header spinlock, which would have to be taken anyway to decrement the
small limit value) whenever the buffer is pinned. (This requires only the
buffer header spinlock, which would have to be taken anyway to increment the
buffer reference count, so it's nearly free.)
The "clock hand" is a buffer index, NextVictimBuffer, that moves circularly