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bcc, bpf_perf_event_output(), and the upcoming Ubuntu 16.04 LTS
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Brendan Gregg
I'm considering creating a directory in bcc called /oldtools, for some older versions that work on the 4.4 kernel. With bpf_perf_event_output() in 4.5, there are many tools that I (or someone) should change to ditch bpf_trace_printk() and use bpf_perf_event_output() instead, which is more efficient and allows multi-user access. Great!However... Ubuntu 16.04 LTS (Xenial Xerus) will be out soon, and likely on the 4.4 kernel. Ubuntu is not the only distribution out there, but a widely used one, including by Netflix. And, given this is an LTS release, I'd expect us to see it in use for a year or more. That gives me hesitation to break these tools for a wide audience, especially one who may be experiencing their first impression of bcc & eBPF. So I'm considering putting some older versions of tools (like execsnoop, opensnoop) in a temporary /oldtools directory, as I bpf_perf_event_output() all the things. In the distant future, we can delete /oldtools. Sound ok? Brendan
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Alexei Starovoitov
makes sense to me.
may be new subdir under tools/ ? Since we have few links on the web pointing to github/iovisor/bcc/tools/ On Thu, Feb 11, 2016 at 2:53 AM, Brendan Gregg via iovisor-dev <iovisor-dev@...> wrote: I'm considering creating a directory in bcc called /oldtools, for some older
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Allan McAleavy
Hi Folks, Has there been a consensus on the way forward with the subdir under tools? I have updated biosnoop and bashreadline to use make use of bpf_perf_event_output and was looking to create a PR. Should I include a move of the current tools to a subdir. If moving I would look to update each of the appropriate man pages with additional info under see also or stability section along the lines of "For some older kernel revisions bpf_perf_event_output may be unavailable, please check for this tool in tools/xyz_dir/" Thanks Allan
On Thu, Feb 11, 2016 at 9:12 AM, Alexei Starovoitov via iovisor-dev <iovisor-dev@...> wrote: makes sense to me.
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Brendan Gregg
On Fri, Feb 12, 2016 at 10:13 AM, Allan McAleavy <allan.mcaleavy@...> wrote:
Yes, lets have tools/old, to keep it simple.
Great! I've been using bpf_perf_event_output() too (see my PR for ext4slower/xfslower), and had a few nits I need to file tickets on (I labeled some things in the code as "workaround", like it not liking u32's in the data_t). So if you ran into similar issues, you weren't alone.
Sounds good. Just put the tool into tools/old, and add "This makes use of a Linux 4.5 feature (bpf_perf_event_output()); for kernels older than 4.5, see the version under tools/old, which uses an older mechanism." Brendan
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