I think I know why this is happening, and I think it is correct. I ran a test again only looking at Dom0 and found that it was similar to Dom1. The
‘read sectors’ from /proc/diskstats were about 2x the pgpgin from
/proc/vmstat. This is whay I see on my physical hardware as well.
The reason that I am not seeing the same results when reading data from Dom1 is because I am only looking at the physical block device (/dev/sda in this case). When I look at the diskstats from physical device /dev/sda and device between used for blkback /dev/tda they show the 2 reads. Since they are both “block devices” I assume they need to page in to make the data available.
So I think this is not really an issue, just a matter of perspective.