Null performance during a test

From: Erwan Velu <erwan_at_seanodes.com>
Date: Fri, 20 Jul 2007 16:30:25 +0200

Hey Jens,

Here come the bw line from a disk_profile_zone test:
    bw (KiB/s) : min= 0, max=66715, per=96.11%, avg=62230.60,
stdev=12736.12

I was very surprised to see 0 as min. I looked into the bw file and
found some lines like :
2193590, 0, 0

I tried to find the number of lines and found 181 null measures.

[root_at_max1 ~]# grep ", 0, 0" client1_bw.log | wc -l
181
[root_at_max1 ~]#

My job have 4569 entries in the bw.log file meaning that near 4% of my
requests reports a null size.

Do you have any idea why I have such results ? Looks like an IO at
0K/sec is nearly impossible for a huge set of sequential requests of
64KB blocks.

This null results turn my average & stdev wrong :/

Thanks,
Erwan
Received on Fri Jul 20 2007 - 16:30:25 CEST

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