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Re: [Ksummit-2008-discuss] DTrace
On Wed, Jul 02, 2008 at 01:06:51PM -0700, Joel Becker wrote:
> 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.
That would be nice. But I'm afraid I normally don't even have access to
the kernel tree on the machine I'm installing to--I usually build a
monolithic kernel and then scp it to the test machines. Is there hope
for me?
--b.
> 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
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