On Tue, 11 Apr 2017 11:38:27 +0200, Jan Kara wrote: > when testing my fix for 0-day reports with writeback throttling I came > across somewhat unexpected behavior with user interface of writeback > throttling. So currently if CFQ is used as an IO scheduler, we disable > writeback throttling because they don't go well together. However when user > has CONFIG_BLK_WBT_SQ=y and switches IO scheduler to NOOP or DEADLINE > writeback throttling still stays disabled. This is somewhat unexpected > especially because the switching of IO scheduler from CFQ to something else > can have happened behind user's back by some udev rule or so. So basically > CONFIG_DEFAULT_CFQ=y and CONFIG_BLK_WBT_SQ=y don't make sense together. :( > So do people thing we should enable WBT if CONFIG_BLK_WBT_SQ=y and IO > scheduler is switched from CFQ to something else? Yes please. If a scheduler doesn't like WBT then that is its own problem. Deadline with WBT has worked fine for me. -h
