Interpreting disk-zone-profile

From: Erwan Velu <erwan_at_seanodes.com>
Date: Fri, 20 Jul 2007 12:57:12 +0200

Sorry to send so many mails on your list, hope you don't find me too
verbose.

I've been running the disk-zone-profile on my disk.

After 5mn, it reaches 100% done and eta = 0. I'm now in this situation
for 10mn, I can see the average rate falling down slowly.

[root_at_max1 ~]# fio disk-zone-profile
/dev/sdb: (g=0): rw=read, bs=64K-64K/64K-64K, ioengine=libaio, iodepth=2
Starting 1 process
Jobs: 1 (f=1): [R] [100.0% done] [ 70802/ 0 kb/s] [eta 00m:00s]

I thought it could be a cache flushing effect but we are O_DIRECT so
couldn't be an explanation....
I see see are libaio so the 100% done could may significate that all ios
have been queued but in that case eta should be set to 0 because as all
IOs haven't been ended we should know how many are remaning and the
average rate of reading.

This jobs reads 256M every 2G, so on a 150G disk and reading at
70MB/sec, this should be very quick isn't it ? Around 5mn maybe...

Do you have any idea how I must interpret this situation ?

Thanks,
Erwan
Received on Fri Jul 20 2007 - 12:57:12 CEST

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