In article <[email protected]>, Jeff Rizzo <[email protected]> wrote: >On 8/20/15 10:52 AM, Taylor R Campbell wrote: >> I'd like to enable dtrace by default on i386, amd64, and arm -- that >> is, setting MKDTRACE=yes in make for the userland tools, and enabling >> options KDTRACE_HOOKS in the kernel for the hooks. >> >> The overhead of KDTRACE_HOOKS in the kernel is a predicted not-taken >> branch in a handful of places. I have not measured the speed impact >> but I expect it to be very small. All logic related to dtrace is >> relegated to a module, so unless you load dtrace.kmod, there's >> negligible memory impact. >> >> The overhead of MKDTRACE=yes in the userland is about 15 MB of dtrace >> tools and libraries on amd64. >> >> The benefits are manifold: low-overhead flexible diagnostics for >> performance and debugging issues in the field with no kernel rebuild >> or reboot. In the past few months while trying to help people debug >> things, my first question has often been `do you have dtrace?'. >> >> Objections? > >PLEASE DO THIS NOW. Err, I mean, "No, no objection from me."
I am fine with this too. christos
