|| ||"Frank Ch. Eigler" <fche-AT-redhat.com> |
|| ||Andrew Morton <akpm-AT-linux-foundation.org> |
|| ||Re: [PATCH 3/3] utrace-based ftrace "process" engine, v2 |
|| ||Sat, 21 Mar 2009 07:51:41 -0400|
|| ||Peter Zijlstra <a.p.zijlstra-AT-chello.nl>, linux-kernel-AT-vger.kernel.org,
Steven Rostedt <rostedt-AT-goodmis.org>, utrace-devel-AT-redhat.com,
Linus Torvalds <torvalds-AT-linux-foundation.org>,
Thomas Gleixner <tglx-AT-linutronix.de>|
|| ||Article, Thread
On Sat, Mar 21, 2009 at 04:19:54AM -0700, Andrew Morton wrote:
> > Utrace is very much tracing material - without the ftrace plugin the
> > whole utrace machinery is just something that provides a _ton_ of
> > hooks to something entirely external: SystemTap mainly.
> Roland's changelogs don't mention systemtap at all afacit.
> That was, umm, major information lossage.
There have been many mixed messages from LKML on the topic - sometimes
mentioning systemtap is forbidden, other times necessary. Sorry about
There are several non-systemtap clients in existence or under
development. You've may have heard of the ptrace cleanup, a
multi-client ptrace replacement, an on-the-fly core dumper, the ftrace
widget, user-space probes. All of these should have somewhat
compelling non-systemtap uses, if that's an important criterion.
> Actually it seems that the whole utrace-ftrace thing is a big
> distraction and could/should just be omitted. This is a systemtap
> feature and should be viewed as such. [...]
utrace is a better way to perform user thread management than what is
there now, and the utrace-ftrace widget shows how to *hook* thread
events such as syscalls in a lighter weight / more managed way than
the first one proposed. (That's one reason we've been participating
in the ftrace discussions.) Of course it can be made to use the fine
syscall pretty-printing code recently added.
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