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Re: [pcp] Dumb question about disk.dev.read_bytes

To: Greg Banks <gnb@xxxxxxxxxxx>
Subject: Re: [pcp] Dumb question about disk.dev.read_bytes
From: nathans@xxxxxxxxxx
Date: Wed, 21 Apr 2010 15:24:41 +1000 (EST)
Cc: PCP Mailing List <pcp@xxxxxxxxxxx>
In-reply-to: <1040297306.139951271827353441.JavaMail.root@xxxxxxxxxxxxxxxxxx>
Sender: nscott@xxxxxxxxxx
----- "Greg Banks" <gnb@xxxxxxxxxxx> wrote:

> 
> UNIT CONVERSION
> All metrics that have the semantics of counters are automatically con‐
> verted to rates over the sample time interval. In interactive mode,
> pmdumptext will also change the units of some metrics so that they are
> easier to comprehend:

So, somehow you're getting into "interactive mode", it looks like.

> o All metrics with space units (bytes to terabytes) are scaled to
> bytes. Note that 1024 bytes with be represented as 1.02K, not
> 1.00K.
> 
> 
> Yet I see pmdumptext reporting the Linux numbers in Kbyte/sec not
> byte/sec like I was expecting. So what's wrong here: the manpage, the
> code, or my reading of the manpage?

What options are you using?  I see this... (Linux)

$ pmdumptext disk.dev.total_bytes -s 2
Wed Apr 21 15:20:34     ?       ?       ?       ?       ?       ?
Wed Apr 21 15:20:35     0.000   518.341 0.000   0.000   0.000   0.000
$ pmdumptext -i disk.dev.total_bytes -s 2
Wed Apr 21 15:20:38          ?       ?       ?       ?       ?       ?
Wed Apr 21 15:20:39      0.00    0.23M   0.00    0.00    0.00    0.00

The first function (checkUnits) here...
http://oss.sgi.com/cgi-bin/gitweb.cgi?p=pcp/pcp-gui.git;a=blob_plain;f=src/dumptext/pmdumptext.cpp;hb=HEAD
...has a comment "// Only scale units if interactive and not raw" which
looks like the underlying mechanism (the test on the next line).

cheers.

-- 
Nathan

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