Canonical Voices

Posts tagged with 'bcc'

Colin Ian King

The BPF Compiler Collection (BCC) is a toolkit for building kernel tracing tools that leverage the functionality provided by the Linux extended Berkeley Packet Filters (BPF).

BCC allows one to write BPF programs with front-ends in Python or Lua with kernel instrumentation written in C.  The instrumentation code is built into sandboxed eBPF byte code and is executed in the kernel.

The BCC github project README file provides an excellent overview and description of BCC and the various available BCC tools.  Building BCC from scratch can be a bit time consuming, however,  the good news is that the BCC tools are now available as a snap and so BCC can be quickly and easily installed just using:

 sudo snap install --devmode bcc  

There are currently over 50 BCC tools in the snap, so let's have a quick look at a few:

cachetop allows one to view the top page cache hit/miss statistics. To run this use:

 sudo bcc.cachetop  

The funccount tool allows one to count the number of times specific functions get called.  For example, to see how many kernel functions with the name starting with "do_" get called per second one can use:

 sudo bcc.funccount "do_*" -i 1  

To see how to use all the options in this tool, use the -h option:

 sudo bcc.funccount -h  

I've found the funccount tool to be especially useful to check on kernel activity by checking on hits on specific function names.

The slabratetop tool is useful to see the active kernel SLAB/SLUB memory allocation rates:

 sudo bcc.slabratetop  

If you want to see which process is opening specific files, one can snoop on open system calls use the opensnoop tool:

 sudo bcc.opensnoop -T

Hopefully this will give you a taste of the useful tools that are available in BCC (I have barely scratched the surface in this article).  I recommend installing the snap and giving it a try.

As it stands,BCC provides a useful mechanism to develop BPF tracing tools and I look forward to regularly updating the BCC snap as more tools are added to BCC. Kudos to Brendan Gregg for BCC!

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Dustin Kirkland

On Monday this week, I was afforded the distinct privilege to deliver the opening keynote at the OpenZFS Developer Summit in San Francisco.  It was a beautiful little event, with a full day of informative presentations and lots of networking during lunch and breaks.

Below, you can view my slides, download the PDF, or watch the talk (starts at 31:10) and demo in its entirety.

Hopefully you'll enjoy the demo -- especially the most interesting raw tracing system new in the Ubuntu 16.04 LTS Linux 4.4 kernel, something called The Berkeley Packet Filter, or "BPF" for short.  I used a series of open source utilities from Brendan Gregg (from Netflix), called iovisor/bcc.  Quoting the on Github:

BCC is a toolkit for creating efficient kernel tracing and manipulation programs, and includes several useful tools and examples. It makes use of extended BPF (Berkeley Packet Filters), formally known as eBPF, a new feature that was first added to Linux 3.15. Much of what BCC uses requires Linux 4.1 and above.
I'll follow up this post with another one, formally introducing BPF and how to install and use bcc in Ubuntu 16.04 LTS, if anyone is interested...


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