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Re: [Ksummit-2008-discuss] DTrace
On Tue, Jul 01, 2008 at 07:13:27PM -0400, Theodore Tso wrote:
> And remember, for the average kernel developer, the question is
> whether using SystemTap is easier than inserting a bunch of printk's
I'll throw in a datapoint here. I recently had to track a
problem down on a distro kernel, and rebuilding distro kernels takes a
lot of time. So I decided to try SystemTap. Once I'd discovered the
magic location of the distro's debuginfo package, systemtap was *WAY*
faster than prink+recompile. I mean, we're talking 30 second turnaround
between "Oh, I'd like to print this other value" and actually printing
it. In the core kernel, not a module. No reboot, no nothin. This is a
huge win.
But I'll never replicate that for my normal work at this rate.
I'm usually floating multiple hand-built mainline kernels with new
work. Just like Ted describes.
> repository or weekly automated snapshots.) So actually, being able to
> install stripped modules and vmlinux into /boot and /linux, and then
> being able to put the unstripped binaries somewhere else, without
> having to use the !@#@! complicated RPM macros by Fedora/RHEL is
> actually **very** important to me.
Me too. I want to be able to say "make install; make
tap_install" in my kernel objdir. "install" does what it always has
done - no change. "tap_install" (or whatever) drops things in eg
/lib/modules/<version>/debug such that systemtap Just Works. It can
error if systemtap isn't installed or is too old. But I shouldn't have
to build a distro package of my kernel, or even understand the
mechanism for building 'debuginfo' bits (even if I do).
Joel
--
"I am working for the time when unqualified blacks, browns, and
women join the unqualified men in running our overnment."
- Sissy Farenthold
Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127