Size of each PHYS_IO

[Lee, Jones]

Dear All,
I just migrate my system from a rp7420 to a rp4440. There is no significant difference on the overall performance with each other. However I find that though the GBL_DISK_PHYS_BYTE_RATE are similar between rp7420 and rp4440, the GBL_DISK_PHYS_IO_RATE of rp4440 has drop 50% compare with rp7420. Does any one know the size of each so-called IO defined by PHYS_IO_RATE? (or the average size if it varied from time to time). Thanks a lot.
BR
Jones