[pve-devel] diskstats : wchar vs write_bytes

[Alexandre DERUMIER]

Hi again,
(sorry to disturb you with all my questions ;)

I was checking rrd io stats for a vm I was installing,
and something strange.

I have a lot of writes, but 
wchar < rchar
but
write_bytes > read_bytes


write_bytes,read_bytes seem to be the correct values, reported in qemu monitor also
I also check on my storage,write_bytes is the correct value.

what's the difference between wchar and write_bytes ?


# cat /proc/356186/io 
rchar: 9209027302
wchar: 149479937
syscr: 23897205
syscw: 8203161
read_bytes: 3060195328
write_bytes: 18257102336
cancelled_write_bytes: 0



qemu monitor:
# info blockstats
drive-ide2: rd_bytes=8130027520 wr_bytes=0 rd_operations=184887 wr_operations=0 flush_operations=0 wr_total_time_ns=0 rd_total_time_ns=29828135558 flush_total_time_ns=0
drive-ide0: rd_bytes=3074498048 wr_bytes=18266386944 rd_operations=257339 wr_operations=275744 flush_operations=2653 wr_total_time_ns=618998308073 rd_total_time_ns=282673829906 flush_total_time_ns=1414696364