Hi, 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? Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
