Date: Wed, 24 Sep 2014 08:09:15 -0700 From: David Wolfskill <david@catwhisker.org> To: freebsd-performance@FreeBSD.org Subject: Re: I like iostat, but... Message-ID: <20140924150915.GC1221@albert.catwhisker.org> In-Reply-To: <5421355D.1020305@freebsd.org> <BD02068D-89C5-42AE-9C06-8F3539492A03@sarenet.es> <20140923121945.8975311d308a1ff088dd90b0@systemdatarecorder.org> <659899B2-1816-41FA-9DED-57416928A1EE@sarenet.es> <20140923113844.6f9e9584965dfd401f6943af@systemdatarecorder.org> <35F9FD7B-6847-4209-A2F9-B1F0ABD01E4C@sarenet.es> <542094B2.5040302@FreeBSD.org>
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On Tue, Sep 23, 2014 at 12:29:22AM +0300, Andriy Gapon wrote:
> On 23/09/2014 00:22, David Wolfskill wrote:
> > ... I rather wish I could get the same information via sysctl. (Well,
> > something seems to be available via the "opaque" kern.devstat.all
> > sysctl(8) variable, but sysctl(8) doesn't display all of it, and parsing
> > it seems as if that would require knowledge about the internals of the
> > system where the data were acquired.)
>=20
> Perhaps sysutils/devstat could be of help?
> ...
On Tue, Sep 23, 2014 at 08:56:54AM +0200, Borja Marcos wrote:
> ...=20
> Reading sysctl from a small C program is not hard at all. I did it for de=
vilator (a data recollector for Orca). And
> there's a lot of data available. An advantage is, you avoid launching sev=
eral processes.
> ...
On Tue, Sep 23, 2014 at 10:45:14AM +0200, Borja Marcos wrote:
> ...=20
> Anyway, for disk stats GEOM offers a nice API. You can get delays per GEO=
M provider, bandwidths, etc.
On Tue, Sep 23, 2014 at 11:38:44AM +0300, Stefan Parvu wrote:
> ...=20
> I gave up parsing sysctl via Perl for disks and network devices. It would=
be
> nice to have devstat properly working via sysctl for disk devices. Simila=
r way
> kern.cp_times does. Currently there is no simple way to extract per disk =
stats from
> sysctl as a Perl or Sh consumer, unless we build a C module to do that.=
=20
Folks, I appreciate the suggestions, but they address problems other
than the one I am trying to solve.
In particular:
* I require that the tool must only depend on components of base FreeBSD;
thus, I don't need to perturb the system I want to measure by
installing otherwise unneeded software on it.
* I am using a shell script (which uses date, sysctl, netstat, and awk)
so I don't need to recompile my data acquisition tool.
* The tasks I am trying to measure are software builds similar to
a stable/10 "make universe" -- but about 2 - 3 times the duration
(and reading and writing a significantly larger amount of data).
Thus, the number of additional processes caused by my probe firing
even as often as once/second is lost in the noise.
> ...
> > If iostat(8) could be taught to (optionally) provide a timestamp, that
> > might suffice.
>=20
> In fact all performance userland tools should be able to nicely produce t=
imestamp
> CSV records which can be used for capacity planning and feed them to an
> analytic product. Something like:
>=20
> 1411445589:4.01:16.03:383.97:1.93:0.29:1.68:0.11:95.99:0.00:0.00:0.00:0.0=
0:123.00:229516.00:570992.00
>=20
> or something like iostat:
>=20
> 1411445733:ada0:0.00:0.00:0.00:0.00:0.00:0.00:0.00
>=20
> where the first field would be always the timestmp, unix time. It is not =
that complicated
> but it does not exist.
The output of my shell script may be described as:
# <record> ::=3D <fieldlist> newline
# <fieldlist> ::=3D <field> | <field> tab <fieldlist>
# <field> ::=3D <tag> : <value>
# <tag> ::=3D [_0-9a-zA-Z][-_.0-9a-zA-Z]+
# <value> ::=3D [^\t\n]*
# Each record will have a field with a tag called "time"; the
# associated value will be the number of seconds since the Epoch,
# but will be coerced as necessary to ensure that it is monotonically
# increasing.
# Note that the colon (":") is a valid character in the value part
# of a field (but not in the tag). Further, there is no whitespace
# on either side of that delimiting colon: everything to the left of the
# colon (up to, but not including, the previous tab, if any) is part of the
# tag; everything to the right of the colon (up to, but not including,
# the next tab or newline) is part of the value.
A prior version of the script output CSV; for this version, I chose to
use the above format because I had situations where some fields showed
up on some lines, but not on others. That tends to make the use of CSV
a bit problematic. (On a machine where I post-process the collected
data, I have some Perl that reads the above format, creates new field
names as necessary to cope with multivariate data (e.g., kern.cp_time or
vm.loadavg), and generates CSV from the result.)
> ...
> My idea of having standard data recorders: sysrec, cpurec, nicrec diskrec=
=20
> which can extract: overall system consumption, per device statistics.
> http://www.systemdatarecorder.org/recording/agents.html=20
> ...
That looks interesting and useful for a broad class of similar problems.
However, as far as I can tell, it is not suitable for the problem(s) I
am trying to solve in this case.
Basically, I have something that works "well enough" for things
like CPU counters, memory usage (at the rather coarse granularity
that top(1) provides, vs. "vmstat -m" output), load avergaes, and
NIC counters, and is readily extensible to any univariate (or simple
list of multivariate) (non-opaque) sysctl OIDs. I'd like to be
able to include information from the I/O subsystem -- in particular,
data that is accessible from "iostat -x".
Peace,
david
--=20
David H. Wolfskill david@catwhisker.org
Taliban: Evil cowards with guns afraid of truth from a 14-year old girl.
See http://www.catwhisker.org/~david/publickey.gpg for my public key.
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