Date: Fri, 05 Apr 2013 11:42:22 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Alfred Perlstein <alfred@ixsystems.com> Cc: arch@FreeBSD.org Subject: collecting statistics / metrics Message-ID: <515E8E6E.4030706@FreeBSD.org> In-Reply-To: <515C68B5.2010006@ixsystems.com> References: <20130401115128.GZ76816@FreeBSD.org> <20130402232606.GC1810@garage.freebsd.pl> <20130403002846.GB15334@onelab2.iet.unipi.it> <20130403100401.GA1349@garage.freebsd.pl> <515C68B5.2010006@ixsystems.com>
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on 03/04/2013 20:36 Alfred Perlstein said the following: > Hey folks, sorry for the top post here, but I just came into this thread. > > Here at iXsystems we've just developed a set of scripts to scrape the various > FreeBSD user land utilities (sysctl, netstat, nfsstat, vmstat, etc, etc) and put > them into graphs based on time. > > The goal is to be able to line up all these metrics with whatever benchmark we > are currently running and be able to see what may be causing issues. > > Potentially you should be able to scroll through the graphs and see things like > "ran out of mbufs @time", "vm system began paging at @time", "buffer deaemon > went nuts @time" > > Then we can take the information back and leverage it to make tuning decisions, > or potentially change kernel algorithms. This is very very useful! > The only problem we have is that every user land tool has its own format, so > along with my team we have written some shell to coerce the output from the > various programs into pseudo-CSV (key/value pair) which can then be post > processed by tools to convert to CSV which can then be put into something like > open office, or put through an R program to graph it. > > I'm hoping to have something shortly. > > What I was hoping to do over the next few days was discuss with people how we > can (or should we even) fix the user land statistics tools to output machine > readable output that can be easily parsed. > > Example: netstat -m (hard to parse) versus 'vmstat -z | grep mbuf' easy to parse. > > The idea of outputting xml is good, CSV is OK, however CSV is problematic as in > the case of sysctl, if new nodes appear, then we can't begin to emit them, we > must either ignore them, or abort, or log them to auxiliary files. Anything > that makes life easier is good. > > I should be able to share our scripts within the next couple of days. Just an alternative idea... I think gathering all this information via plugins to e.g. collectd could be more flexible and less processing / parsing intensive. That would allow to avoid unnecessary formatting and re-parsing and to store the data in a convenient format. Ideally it would be great to have an umbrella library on top of sysctl, devstat, etc that would expose various stats in a convenient form. Another thing of convenience would be an ability to know which sysctls are actually stats. I think that you have already done work towards this goal. There are certain heuristics that may help to distinguish stats from knobs, constants, etc, but the explicit "this is a metric" should be used. Of course, it would take a lot of work to properly mark all the sysctls. Just thinking out loud. -- Andriy Gapon
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