Before commit 3cec5c77d617 buf_daemon() went to longer 1s sleep if numdirtybuffers <= lodirtybuffers. After that commit new condition !BIT_EMPTY(BUF_DOMAINS, &bdlodirty) is opposite -- true when one more more domain is above lodirtybuffers. As result, on freshly booted system with no dirty buffers buf_daemon() wakes up 10 times per second.