I use mpstat a lot and at times want to know if a numa node is busy or at times a specific core. Previously I would post process the mpstat data after comparing the data to the output of lscpu. A while ago I wrote a perl script to map this out and reworked this […]
Overview This post will cover some slides from my presentation of the same name which I have presented at a few conferences. I have omitted the tooling setup and graphics of issues as this just shows impact not the reasoning behind it. Traditional bottleneck In the above slide we can see that the time to […]
We were seeing some spike in CPU usage every 15 minutes on some new servers. As these systems were idle i.e. no workload apart from the operating system this makes an investigation slightly easier as we don’t have any application workloads to add to the mix. Below we can see an example of the spikes […]
I was made aware that eBPF was available now in RHEL via the below tweet from Brendan Gregg. As our main distro is RHEL I was intrigued to see what the release looked like and what was available. For those who don’t know the bcc-tools package contains the eBPF bcc toolset which allows new insights into […]
I have been recently working on the Meltdown and Spectre bugs and assessing what the impact will be to our servers. As part of this testing we used a tool called SLOB which we use to stress memory accesses (cached reads) and also I/O based on random and sequential I/O. The database in use was […]
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