On Tue, May 06, 2025 at 02:03:37PM +0300, Anton Gavriliuk wrote: > > So is this MD chunk size related? i.e. what is the chunk size > > the MD device? Is it smaller than the IO size (256kB) or larger? > > Does the regression go away if the chunk size matches the IO size, > > or if the IO size vs chunk size relationship is reversed? > > According to the output below, the chunk size is 512K, Ok. `iostat -dxm 5` output during the fio run on both kernels will give us some indication of the differences in IO patterns, queue depths, etc. Silly question: if you use DM to create the same RAID 0 array with a dm table such as: 0 75011629056 striped 12 1024 /dev/nvme7n1 0 /dev/nvme0n1 0 .... /dev/nvme12n1 0 to create a similar 38TB raid 0 array, do you see the same perf degradation? -Dave. -- Dave Chinner david@xxxxxxxxxxxxx
