|From:||"Frank Ch. Eigler" <fche-AT-redhat.com>|
|To:||Andrew Morton <akpm-AT-linux-foundation.org>|
|Subject:||Re: [PATCH 3/3] utrace-based ftrace "process" engine, v2|
|Date:||Sat, 21 Mar 2009 07:51:41 -0400|
|Cc:||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>|
Hi - 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 that. 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. - FChE
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