title: Intel NVMe drive Performance degradation with xfs filesystem with sector size other than 4096
body: <p>I am working with NVMe card on linux(Ubuntu 14.04). 
  I am finding some performance degradation for Intel NVMe card when formatted with xfs file system with its default sector size(512). or any other sector size less than 4096.</p>
  
  <p>In the experiment I  formatted the card with xfs filesystem with default options. I tried running fio with 64k block size on an arm64 platform with 64k page size.
  This is the command used 
   <code>fio --rw=randread --bs=64k --ioengine=libaio   --iodepth=8 --direct=1 --group_reporting --name=Write_64k_1 --numjobs=1 --runtime=120 --filename=new  --size=20G</code></p>
  
  <p>I could get only the below values</p>
  
  <p><em>Run status group 0 (all jobs):
     READ: io=20480MB, <strong>aggrb=281670KB/s</strong>, minb=281670KB/s, maxb=281670KB/s, mint=744454msec, maxt=74454msec
  Disk stats (read/write):
    nvme0n1: ios=326821/8, merge=0/0, ticks=582640/0, in_queue=582370, util=99.93%</em></p>
  
  <p>I tried formatting as follows:</p>
  
  <pre><code>mkfs.xfs -f -s size=4096 /dev/nvme0n1
  </code></pre>
  
  <p>then the values were :</p>
  
  <p><em>Run status group 0 (all jobs):
     READ: io=20480MB, <strong>aggrb=781149KB/s</strong>, minb=781149KB/s, maxb=781149KB/s, mint=266
  847msec, maxt=26847msec
  Disk stats (read/write):
    nvme0n1: ios=326748/7, merge=0/0, ticks=200270/0, in_queue=200350, util=99.51%</em></p>
  
  <p>I find no performance degradation when used with </p>
  
  <ul>
  <li>4k page size</li>
  <li>Any fio block size lesser than 64k</li>
  <li>With ext4 fs with default configs</li>
  </ul>
  
  <p>What could be the issue? Is this any alignment issue? What Am I missing here? Any help appreciated</p>