WB_FRN_HIST_THR_SLOTS  242 fs/fs-writeback.c #define WB_FRN_HIST_MAX_SLOTS	(WB_FRN_HIST_THR_SLOTS / 2 + 1)
WB_FRN_HIST_THR_SLOTS  696 fs/fs-writeback.c 		if (hweight32(history) > WB_FRN_HIST_THR_SLOTS)