Re: dtrace by default

[christos%astron.com@localhost (Christos Zoulas)]

In article <55D616BB.5050601%tastylime.net@localhost>,
Jeff Rizzo  <riz%tastylime.net@localhost> 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