On Fri, Apr 28, 2017 at 11:59:34AM +0200, Jan Kara wrote: > Commit b685d3d65ac7 "block: treat REQ_FUA and REQ_PREFLUSH as > synchronous" removed REQ_SYNC flag from WRITE_FUA implementation. Since > JBD2 strips REQ_FUA and REQ_FLUSH flags from submitted IO when the > filesystem is mounted with nobarrier mount option, journal superblock > writes ended up being async writes after this patch and that caused > heavy performance regression for dbench4 benchmark with high number of > processes. In my test setup with HP RAID array with non-volatile write > cache and 32 GB ram, dbench4 runs with 8 processes regressed by ~25%. > > Fix the problem by making sure journal superblock writes are always > treated as synchronous since they generally block progress of the > journalling machinery and thus the whole filesystem. > > Fixes: b685d3d65ac791406e0dfd8779cc9b3707fea5a3 > CC: stable@xxxxxxxxxxxxxxx > Signed-off-by: Jan Kara <jack@xxxxxxx> Thanks, applied. - Ted