_wmd

The joy with bpftrace (and dtrace before it) for me is this ease with which 'synthetic' profiling events can be constructed from multiple underlying events. This can be used to, for example, only record the latency of malloc() while at least one TCP connection has been accepted and some particular function in your binary has already run at least once with its third parameter having a particular value

The offwake.bt example from the article is the closest to that, but it doesn't hook any userspace functions (like malloc). That's totally possible and extremely easy -- events can be mixed from wherever in the same script and, barring some knowledge like the fact the script is running on every CPU simultaneously, things just magically work

The main problem with bpftrace is that it's a pain in the ass to compile from source just now. A tool as useful as this really wants to be available on every machine by default

I think the keyword here is transparency -- later designs (even stuff like MPI) explicitly expose the topology of the available hardware. SMP is the closest thing we've ever got to true transparency, and then only for 80% of cases, and for those only because the compute nodes have very similar locality and e.g. memory bandwidth

Even SMP requires careful control if you want to get anything close to the actual performance of the underlying hardware, and the topology is once again very explicit

If you can't answer this question for yourself, why do you think you'd be capable of modifying the factory default? Memory management is one of the most complex pieces of a modern OS

The BBC article mentions many died on the stairs to the roof. Sounds like a locked door could have been involved

After the smear campaign and mass roasting he received less than 2 months ago, it's not hard to understand why any charitable intentions he had may have completely dried up

Python 2.1 or 2.2, sure

So in response to a catastrophic failure due to testing in prod, they're going to push out a brand new regex engine with an ETA of 2 weeks. Can anyone say testing in prod?

The constant use of 'I' and 'me' (19 occurrences in total) deeply tarnishes this report, and repeatedly singling out a responsible engineer, nameless or not, is a failure in its own right. This was a collective failure, any individual identity is totally irrelevant. We're not looking for an account of your superman-like heroism, sprinting from meeting rooms or otherwise, we want to know whether anything has been learned in the 2 years since Cloudflare leaked heap all across the Internet without noticing, and the answer to that seems fantastically clear.

hey! Do you know if anyone is working on getting bpftrace to use BTF yet? Looks like one of the final chunks landed in Linux 5.2