On Sun, May 31, 2015 at 11:02 PM, Ming Lin <mlin@xxxxxxxxxx> wrote: > On Thu, 2015-05-28 at 01:36 +0100, Alasdair G Kergon wrote: >> On Wed, May 27, 2015 at 04:42:44PM -0700, Ming Lin wrote: >> > Here are fio results of XFS on a DM stripped target with 2 SSDs + 1 HDD. >> > Does it make sense? >> >> To stripe across devices with different characteristics? >> >> Some suggestions. >> >> Prepare 3 kernels. >> O - Old kernel. >> M - Old kernel with merge_bvec_fn disabled. >> N - New kernel. >> >> You're trying to search for counter-examples to the hypothesis that >> "Kernel N always outperforms Kernel O". Then if you find any, trying >> to show either that the performance impediment is small enough that >> it doesn't matter or that the cases are sufficiently rare or obscure >> that they may be ignored because of the greater benefits of N in much more >> common cases. >> >> (1) You're looking to set up configurations where kernel O performs noticeably >> better than M. Then you're comparing the performance of O and N in those >> situations. >> >> (2) You're looking at other sensible configurations where O and M have >> similar performance, and comparing that with the performance of N. > > I didn't find case (1). > > But the important thing for this series is to simplify block layer > based on immutable biovecs. I don't expect performance improvement. > > Here is the changes statistics. > > "68 files changed, 336 insertions(+), 1331 deletions(-)" > > I run below 3 test cases to make sure it didn't bring any regressions. > Test environment: 2 NVMe drives on 2 sockets server. > Each case run for 30 minutes. > > 2) btrfs radi0 > > mkfs.btrfs -f -d raid0 /dev/nvme0n1 /dev/nvme1n1 > mount /dev/nvme0n1 /mnt > > Then run 8K read. > > [global] > ioengine=libaio > iodepth=64 > direct=1 > runtime=1800 > time_based > group_reporting > numjobs=4 > rw=read > > [job1] > bs=8K > directory=/mnt > size=1G > > 2) ext4 on MD raid5 > > mdadm --create /dev/md0 --level=5 --raid-devices=2 /dev/nvme0n1 /dev/nvme1n1 > mkfs.ext4 /dev/md0 > mount /dev/md0 /mnt > > fio script same as btrfs test > > 3) xfs on DM stripped target > > pvcreate /dev/nvme0n1 /dev/nvme1n1 > vgcreate striped_vol_group /dev/nvme0n1 /dev/nvme1n1 > lvcreate -i2 -I4 -L250G -nstriped_logical_volume striped_vol_group > mkfs.xfs -f /dev/striped_vol_group/striped_logical_volume > mount /dev/striped_vol_group/striped_logical_volume /mnt > > fio script same as btrfs test > > ------ > > Results: > > 4.1-rc4 4.1-rc4-patched > btrfs 1818.6MB/s 1874.1MB/s > ext4 717307KB/s 714030KB/s > xfs 1396.6MB/s 1398.6MB/s Hi Alasdair & Mike, Would you like these numbers? I'd like to address your concerns to move forward. Thanks. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
