On Fri, Aug 17, 2012 at 11:13:18PM +0800, Fengguang Wu wrote: > > Obviously the major regressions happen to the 100dd over raid cases. > Some 10dd cases are also impacted. > > The attached graphs show that everything becomes more fluctuated in > 3.6.0-rc1 for the lkp-nex04/RAID0-12HDD-thresh=8G/ext4-100dd-1 case. Hmm... I'm not seeing any differences in the block allocation code, or in ext4's buffered writeback code paths, which would be the most likely cause of such problems. Maybe a quick eyeball of the blktrace to see if we're doing something pathalogically stupid? You could also try running a filefrag -v on a few of the dd files to see if there's any significant difference, although as I said, there doesn't look like there was any significant changes in the block allocation code between v3.5 and v3.6-rc1 --- although I suppose changes in timeing could have have caused the block allocation decisions to be different, so it's worth checking that out. Thanks, regards, - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
