lss_rea_bytes and bytes_written do not always match perf html report

In 7 indexes bloom filter test for build 5177, I can see that the 2 stats approximately match rbps and wbps from html report.

rbps 300-400 MB/s

wbps 100-150 MB/s

2021-05-19T15:43:59.874-07:00 [Info] Periodic Aggregated StorageStats:

"lss_read_bs":                   2976503344353,

"bytes_written":                 1906122153984,

2021-05-19T16:13:59.870-07:00 [Info] Periodic Aggregated StorageStats:

"lss_read_bs":                   3528014358936,  +551511014583  306395008/s

"bytes_written":                 2066645012480,  +160522858496  89179365/s 

{nofomat}

For 10K index incremental build test, the number seems to be off, especially for lss_read_bs.

rbps read 150 MB/s
wbps write 125 MB/s

2021-05-23T23:02:54.037-07:00 [Info] Periodic Aggregated StorageStats:
"lss_read_bs": 1382967959770,
"bytes_written": 574250827776,

2021-05-23T23:32:53.544-07:00 [Info] Periodic Aggregated StorageStats:
"lss_read_bs": 2050042223997, 667074264227 370596813/s
"bytes_written": 695640932352, 121390104576 67438946/s