Project Description
The sar(1) tool, from the openSUSE package "sysstat", provides a comprehensive method for collecting performance data on a running system.
There isn't, however, a satisfactory way to display historical sar data. It is not uncommon for users who experience a performance degradation to include a few days worth of sar archives in their bug reports. The experts looking into the report often resort to scan these archives using text-oriented utilities such as sed and awk, which may fail to reveal the story hidden behind the data.
We aim at devising a method and tool to visualize large historical sar datasets.
Goal for this Hackweek
Take one or two sample sar datasets and feed them into Grafana[LINK], the Perfetto trace viewer[LINK] and Performance Co-Pilot (PCP)[LINK]. The solution of choice will need to compare favorably with my two previous sar visualization attempts made with ad-hoc scripts: [LINK-1][LINK-2]. Evaluate the outcome, write a report and select one single tool to focus future efforts on.
Prior art
To the best of my knowledge, these are the methods currently available for plotting sar data:
- kSar[MAYBE-LINK-1][MAYBE-LINK-2][MAYBE-LINK-3] Ksar is a self-contained Java GUI. This tool is advertised in our openSUSE Tuning Guide, chapter 2 "System monitoring utilities", section 2.1.3.2 "Visualizing
sardata"[LINK] although we don't have a package for it. Its drawback is it can display asardatafile at a time: assarwrites one datafile per day, to visualize a week worth of archives one has to have multiple kSar windows open. The resulting charts will have different Y axis scales, which makes them difficult to compare. You can find a set of kSar screenshots illustrating this usability problem here: [LINK](requires SUSE confluence login). - sadf -g
sadf -g your_datafile [ -- sar_options ] > output.svgsadf(1) can emit svg files that can be viewed in web browsers. The same limitation of kSar applies here: multiple days require multiple plots. - sar2pcp[LINK] There exist a Performance Co-Pilot (PCP) plugin to import sar data, which we package in openSUSE as "pcp-import-sar2pcp". Last time I checked, sar2pcp had to be invoked with
LD_PRELOAD=/usr/lib64/libpcp_import.sobecause that shared library wasn't correctly linked in the build of the package. That can easily be fixed, but it's unclear to me how well thesar+ PCP combination works, as I haven't yet tried it. It could very well suffer from the one-day-per-plot limitation of the previous two tools. The feature is advertised in bothsarand pcp's documentation: - sadf -j
sadf -j your_datafile [ -- sar_options ] > output.jsonConverting sar data to json, then write an ad-hoc script to produce the charts. This is what I've done in the past, but writing special-purpose code every time takes energy away from actually analyzing the data and debugging the problem at hand. The experience was valuable though, as it showed what these charts should look like (see [LINK-1][LINK-2])
Tentative plan
It seems a sensible choice to leverage an existing graphing tool and make adjustments so that it's tailored at sar data (eg. create a plug-in or a new plot type within an existing framework). Candidates are Grafana (web tool), the Perfetto trace visualizer (web tool) and Performance Co-Pilot (desktop app). I'm slightly biased towards interactive charts as opposed to static images since zooming in/out and moving around the data range may help exploring the dataset. Interactivity is best achieved with web based tools, which offer the possibility of sharing access to the visualization with a URL, without the need for the recipient to install new software locally.
![[LINK]](https://confluence.suse.com/download/attachments/515801221/ksar-screeshots.jpg?api=v2){kind=link}
Looking for hackers with the skills:
grafana performance perfetto performance-co-pilot pcp sar visualization monitoring observability
This project is part of:
Hack Week 22 Hack Week 23
Activity
Comments
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over 2 years ago by ggherdovich | Reply
Hello Heikki, thanks for commenting. What I'm taking from the status of sar+pcp interoperability in openSUSE is that no-one has ever used it. The problem you mention, plus the ones I already knew about, are failures that you'd notice immediately as you launch the tool. So on one side those are fixable with one-line edits in the spec file of the package, but on the other one they show that in essence the sar+pcp combo is uncharted territory, in my estimation.
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over 2 years ago by heikkiyp | Reply
Also noted that with later sysstat version you can convert to pcp supported format directly without the need of sar2pcp tool . The newer syststat is not available for SLE12 branch .. You have to use SLE15 or Leap or TW version . Sa files from SLE12 branch needs conversion anyway as sar2pcp will complain the format .
Most usable way to use pcp is on SLE15 or TW or LEAP . Convert the sa files with :
sadf -l -O pcparchive=sample02 sa20230125 -- -A
Style command and then using pmchart tool ..
Combining is easy .. pmlogextract sample01 sample02 looongsample
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over 2 years ago by ggherdovich | Reply
That's fantastic information Heikki! Thanks for sharing! I haven't tried the sar->pcp conversion technique you suggest (I'll do it soon), but I imagine the limitation you mention (sadf must be from SLE-15 or later) is not so severe, because I suspect the user can still collect sar data using a SLE-12 sar daemon, it's only the person analyzing the data that must have a recent sysstat to do the format conversion. I'd expect the new sadf can still read old archives. Again, thanks for pointing this out!
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almost 2 years ago by ggherdovich | Reply
Hi Paolo, thanks for the link. Looks like a node app that can be deployed on premises. I need to try hosting a local instance of that "sargraph" and see how it does on some sample datasets I have.
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